import * as assert from "assert"
import { unstable as Automerge } from "../src"
import { assertEqualsOneOf } from "./helpers"
import { decodeChange } from "./legacy/columnar"

const UUID_PATTERN = /^[0-9a-f]{32}$/
const OPID_PATTERN = /^[0-9]+@([0-9a-f][0-9a-f])*$/

// CORE FEATURES
//
// TODO - Cursors
// TODO - Tables
// TODO - on-pass load() & reconstruct change from opset
// TODO - micro-patches (needed for fully hydrated object in js)
// TODO - valueAt(heads) / GC
//
// AUTOMERGE UNSUPPORTED
//
// TODO - patchCallback

describe("Automerge", () => {
  describe("initialization ", () => {
    it("should initially be an empty map", () => {
      const doc = Automerge.init()
      assert.deepStrictEqual(doc, {})
    })

    it("should allow instantiating from an existing object", () => {
      const initialState = { birds: { wrens: 3, magpies: 4 } }
      const doc = Automerge.from(initialState)
      assert.deepStrictEqual(doc, initialState)
    })

    it("should allow merging of an object initialized with `from`", () => {
      let doc1 = Automerge.from({ cards: [] })
      let doc2 = Automerge.merge(Automerge.init(), doc1)
      assert.deepStrictEqual(doc2, { cards: [] })
    })

    it("should allow passing an actorId when instantiating from an existing object", () => {
      const actorId = "1234"
      let doc = Automerge.from({ foo: 1 }, actorId)
      assert.strictEqual(Automerge.getActorId(doc), "1234")
    })

    it("accepts an empty object as initial state", () => {
      const doc = Automerge.from({})
      assert.deepStrictEqual(doc, {})
    })

    it("accepts an array as initial state, but converts it to an object", () => {
      // @ts-ignore
      const doc = Automerge.from(["a", "b", "c"])
      assert.deepStrictEqual(doc, { "0": "a", "1": "b", "2": "c" })
    })

    it("accepts strings as initial values, but treats them as an array of characters", () => {
      // @ts-ignore
      const doc = Automerge.from("abc")
      assert.deepStrictEqual(doc, { "0": "a", "1": "b", "2": "c" })
    })

    it("ignores numbers provided as initial values", () => {
      // @ts-ignore
      const doc = Automerge.from(123)
      assert.deepStrictEqual(doc, {})
    })

    it("ignores booleans provided as initial values", () => {
      // @ts-ignore
      const doc1 = Automerge.from(false)
      assert.deepStrictEqual(doc1, {})
      // @ts-ignore
      const doc2 = Automerge.from(true)
      assert.deepStrictEqual(doc2, {})
    })
  })

  describe("sequential use", () => {
    let s1: Automerge.Doc<any>, s2: Automerge.Doc<any>
    beforeEach(() => {
      s1 = Automerge.init("aabbcc")
    })

    it("should not mutate objects", () => {
      s2 = Automerge.change(s1, doc => (doc.foo = "bar"))
      assert.strictEqual(s1.foo, undefined)
      assert.strictEqual(s2.foo, "bar")
    })

    it("changes should be retrievable", () => {
      const change1 = Automerge.getLastLocalChange(s1)
      s2 = Automerge.change(s1, doc => (doc.foo = "bar"))
      const change2 = Automerge.getLastLocalChange(s2)
      assert.strictEqual(change1, undefined)
      const change = Automerge.decodeChange(change2!)
      assert.deepStrictEqual(change, {
        actor: change.actor,
        deps: [],
        seq: 1,
        startOp: 1,
        hash: change.hash,
        message: null,
        time: change.time,
        ops: [
          { obj: "_root", key: "foo", action: "makeText", pred: [] },
          {
            action: "set",
            elemId: "_head",
            insert: true,
            obj: "1@aabbcc",
            pred: [],
            value: "b",
          },
          {
            action: "set",
            elemId: "2@aabbcc",
            insert: true,
            obj: "1@aabbcc",
            pred: [],
            value: "a",
          },
          {
            action: "set",
            elemId: "3@aabbcc",
            insert: true,
            obj: "1@aabbcc",
            pred: [],
            value: "r",
          },
        ],
      })
    })

    it("should not register any conflicts on repeated assignment", () => {
      assert.strictEqual(Automerge.getConflicts(s1, "foo"), undefined)
      s1 = Automerge.change(s1, "change", doc => (doc.foo = "one"))
      assert.strictEqual(Automerge.getConflicts(s1, "foo"), undefined)
      s1 = Automerge.change(s1, "change", doc => (doc.foo = "two"))
      assert.strictEqual(Automerge.getConflicts(s1, "foo"), undefined)
    })

    describe("changes", () => {
      it("should group several changes", () => {
        s2 = Automerge.change(s1, "change message", doc => {
          doc.first = "one"
          assert.strictEqual(doc.first, "one")
          doc.second = "two"
          assert.deepStrictEqual(doc, {
            first: "one",
            second: "two",
          })
        })
        assert.deepStrictEqual(s1, {})
        assert.deepStrictEqual(s2, { first: "one", second: "two" })
      })

      it("should freeze objects if desired", () => {
        s1 = Automerge.init({ freeze: true })
        s2 = Automerge.change(s1, doc => (doc.foo = "bar"))
        try {
          // @ts-ignore
          s2.foo = "lemon"
        } catch (e) {}
        assert.strictEqual(s2.foo, "bar")

        let deleted = false
        try {
          // @ts-ignore
          deleted = delete s2.foo
        } catch (e) {}
        assert.strictEqual(s2.foo, "bar")
        assert.strictEqual(deleted, false)

        Automerge.change(s2, () => {
          try {
            // @ts-ignore
            s2.foo = "lemon"
          } catch (e) {}
          assert.strictEqual(s2.foo, "bar")
        })

        assert.throws(() => {
          Object.assign(s2, { x: 4 })
        })
        assert.strictEqual(s2.x, undefined)
      })

      it("should allow repeated reading and writing of values", () => {
        s2 = Automerge.change(s1, "change message", doc => {
          doc.value = "a"
          assert.strictEqual(doc.value, "a")
          doc.value = "b"
          doc.value = "c"
          assert.strictEqual(doc.value, "c")
        })
        assert.deepStrictEqual(s1, {})
        assert.deepStrictEqual(s2, { value: "c" })
      })

      it("should not record conflicts when writing the same field several times within one change", () => {
        s1 = Automerge.change(s1, "change message", doc => {
          doc.value = "a"
          doc.value = "b"
          doc.value = "c"
        })
        assert.strictEqual(s1.value, "c")
        assert.strictEqual(Automerge.getConflicts(s1, "value"), undefined)
      })

      it("should return the unchanged state object if nothing changed", () => {
        s2 = Automerge.change(s1, () => {})
        assert.strictEqual(s2, s1)
      })

      it("should ignore field updates that write the existing value", () => {
        s1 = Automerge.change(s1, doc => (doc.field = 123))
        s2 = Automerge.change(s1, doc => (doc.field = 123))
        assert.strictEqual(s2, s1)
      })

      it("should not ignore field updates that resolve a conflict", () => {
        s2 = Automerge.merge(Automerge.init(), s1)
        s1 = Automerge.change(s1, doc => (doc.field = 123))
        s2 = Automerge.change(s2, doc => (doc.field = 321))
        s1 = Automerge.merge(s1, s2)
        assert.strictEqual(
          Object.keys(Automerge.getConflicts(s1, "field")!).length,
          2
        )
        const resolved = Automerge.change(s1, doc => (doc.field = s1.field))
        assert.notStrictEqual(resolved, s1)
        assert.deepStrictEqual(resolved, { field: s1.field })
        assert.strictEqual(Automerge.getConflicts(resolved, "field"), undefined)
      })

      it("should ignore list element updates that write the existing value", () => {
        s1 = Automerge.change(s1, doc => (doc.list = [123]))
        s2 = Automerge.change(s1, doc => (doc.list[0] = 123))
        assert.strictEqual(s2, s1)
      })

      it("should not ignore list element updates that resolve a conflict", () => {
        s1 = Automerge.change(s1, doc => (doc.list = [1]))
        s2 = Automerge.merge(Automerge.init(), s1)
        s1 = Automerge.change(s1, doc => (doc.list[0] = 123))
        s2 = Automerge.change(s2, doc => (doc.list[0] = 321))
        s1 = Automerge.merge(s1, s2)
        assert.deepStrictEqual(Automerge.getConflicts(s1.list, 0), {
          [`3@${Automerge.getActorId(s1)}`]: 123,
          [`3@${Automerge.getActorId(s2)}`]: 321,
        })
        const resolved = Automerge.change(s1, doc => (doc.list[0] = s1.list[0]))
        assert.deepStrictEqual(resolved, s1)
        assert.notStrictEqual(resolved, s1)
        assert.strictEqual(Automerge.getConflicts(resolved.list, 0), undefined)
      })

      it("should sanity-check arguments", () => {
        s1 = Automerge.change(s1, doc => (doc.nested = {}))
        assert.throws(() => {
          // @ts-ignore
          Automerge.change({}, doc => (doc.foo = "bar"))
        }, /must be the document root/)
        assert.throws(() => {
          // @ts-ignore
          Automerge.change(s1.nested, doc => (doc.foo = "bar"))
        }, /must be the document root/)
      })

      it("should not allow nested change blocks", () => {
        assert.throws(() => {
          Automerge.change(s1, doc1 => {
            Automerge.change(doc1, doc2 => {
              // @ts-ignore
              doc2.foo = "bar"
            })
          })
        }, /Calls to Automerge.change cannot be nested/)
        assert.throws(() => {
          s1 = Automerge.change(s1, doc1 => {
            s2 = Automerge.change(s1, doc2 => (doc2.two = 2))
            doc1.one = 1
          })
        }, /Attempting to change an outdated document/)
      })

      it("should not allow the same base document to be used for multiple changes", () => {
        assert.throws(() => {
          Automerge.change(s1, doc => (doc.one = 1))
          Automerge.change(s1, doc => (doc.two = 2))
        }, /Attempting to change an outdated document/)
      })

      it("should allow a document to be cloned", () => {
        s1 = Automerge.change(s1, doc => (doc.zero = 0))
        s2 = Automerge.clone(s1)
        s1 = Automerge.change(s1, doc => (doc.one = 1))
        s2 = Automerge.change(s2, doc => (doc.two = 2))
        assert.deepStrictEqual(s1, { zero: 0, one: 1 })
        assert.deepStrictEqual(s2, { zero: 0, two: 2 })
        Automerge.free(s1)
        Automerge.free(s2)
      })

      it("should work with Object.assign merges", () => {
        s1 = Automerge.change(s1, doc1 => {
          doc1.stuff = { foo: "bar", baz: "blur" }
        })
        s1 = Automerge.change(s1, doc1 => {
          doc1.stuff = Object.assign({}, doc1.stuff, { baz: "updated!" })
        })
        assert.deepStrictEqual(s1, { stuff: { foo: "bar", baz: "updated!" } })
      })

      it("should support Date objects in maps", () => {
        const now = new Date()
        s1 = Automerge.change(s1, doc => (doc.now = now))
        let changes = Automerge.getAllChanges(s1)
        ;[s2] = Automerge.applyChanges(Automerge.init(), changes)
        assert.strictEqual(s2.now instanceof Date, true)
        assert.strictEqual(s2.now.getTime(), now.getTime())
      })

      it("should support Date objects in lists", () => {
        const now = new Date()
        s1 = Automerge.change(s1, doc => (doc.list = [now]))
        let changes = Automerge.getAllChanges(s1)
        ;[s2] = Automerge.applyChanges(Automerge.init(), changes)
        assert.strictEqual(s2.list[0] instanceof Date, true)
        assert.strictEqual(s2.list[0].getTime(), now.getTime())
      })

      it("should call patchCallback if supplied", () => {
        const callbacks: Array<{
          patches: Array<Automerge.Patch>
          before: Automerge.Doc<any>
          after: Automerge.Doc<any>
        }> = []
        const s2 = Automerge.change(
          s1,
          {
            patchCallback: (patches, before, after) =>
              callbacks.push({ patches, before, after }),
          },
          doc => {
            doc.birds = ["Goldfinch"]
          }
        )
        assert.strictEqual(callbacks.length, 1)
        assert.deepStrictEqual(callbacks[0].patches[0], {
          action: "put",
          path: ["birds"],
          value: [],
        })
        assert.deepStrictEqual(callbacks[0].patches[1], {
          action: "insert",
          path: ["birds", 0],
          values: [""],
        })
        assert.deepStrictEqual(callbacks[0].patches[2], {
          action: "splice",
          path: ["birds", 0, 0],
          value: "Goldfinch",
        })
        assert.strictEqual(callbacks[0].before, s1)
        assert.strictEqual(callbacks[0].after, s2)
      })

      it("should call a patchCallback set up on document initialisation", () => {
        const callbacks: Array<{
          patches: Array<Automerge.Patch>
          before: Automerge.Doc<any>
          after: Automerge.Doc<any>
        }> = []
        s1 = Automerge.init({
          patchCallback: (patches, before, after) =>
            callbacks.push({ patches, before, after }),
        })
        const s2 = Automerge.change(s1, doc => (doc.bird = "Goldfinch"))
        assert.strictEqual(callbacks.length, 1)
        assert.deepStrictEqual(callbacks[0].patches[0], {
          action: "put",
          path: ["bird"],
          value: "",
        })
        assert.deepStrictEqual(callbacks[0].patches[1], {
          action: "splice",
          path: ["bird", 0],
          value: "Goldfinch",
        })
        assert.strictEqual(callbacks[0].before, s1)
        assert.strictEqual(callbacks[0].after, s2)
      })
    })

    describe("emptyChange()", () => {
      it("should append an empty change to the history", () => {
        s1 = Automerge.change(s1, "first change", doc => (doc.field = 123))
        s2 = Automerge.emptyChange(s1, "empty change")
        assert.notStrictEqual(s2, s1)
        assert.deepStrictEqual(s2, s1)
        assert.deepStrictEqual(
          Automerge.getHistory(s2).map(state => state.change.message),
          ["first change", "empty change"]
        )
      })

      it("should reference dependencies", () => {
        s1 = Automerge.change(s1, doc => (doc.field = 123))
        s2 = Automerge.merge(Automerge.init(), s1)
        s2 = Automerge.change(s2, doc => (doc.other = "hello"))
        s1 = Automerge.emptyChange(Automerge.merge(s1, s2))
        const history = Automerge.getHistory(s1)
        const emptyChange = history[2].change
        assert.deepStrictEqual(
          emptyChange.deps,
          [history[0].change.hash, history[1].change.hash].sort()
        )
        assert.deepStrictEqual(emptyChange.ops, [])
      })
    })

    describe("root object", () => {
      it("should handle single-property assignment", () => {
        s1 = Automerge.change(s1, "set bar", doc => (doc.foo = "bar"))
        s1 = Automerge.change(s1, "set zap", doc => (doc.zip = "zap"))
        assert.strictEqual(s1.foo, "bar")
        assert.strictEqual(s1.zip, "zap")
        assert.deepStrictEqual(s1, { foo: "bar", zip: "zap" })
      })

      it("should allow floating-point values", () => {
        s1 = Automerge.change(s1, doc => (doc.number = 1589032171.1))
        assert.strictEqual(s1.number, 1589032171.1)
      })

      it("should handle multi-property assignment", () => {
        s1 = Automerge.change(s1, "multi-assign", doc => {
          Object.assign(doc, { foo: "bar", answer: 42 })
        })
        assert.strictEqual(s1.foo, "bar")
        assert.strictEqual(s1.answer, 42)
        assert.deepStrictEqual(s1, { foo: "bar", answer: 42 })
      })

      it("should handle root property deletion", () => {
        s1 = Automerge.change(s1, "set foo", doc => {
          doc.foo = "bar"
          doc.something = null
        })
        s1 = Automerge.change(s1, "del foo", doc => {
          delete doc.foo
        })
        assert.strictEqual(s1.foo, undefined)
        assert.strictEqual(s1.something, null)
        assert.deepStrictEqual(s1, { something: null })
      })

      it("should follow JS delete behavior", () => {
        s1 = Automerge.change(s1, "set foo", doc => {
          doc.foo = "bar"
        })
        let deleted: any
        s1 = Automerge.change(s1, "del foo", doc => {
          deleted = delete doc.foo
        })
        assert.strictEqual(deleted, true)
        let deleted2: any
        assert.doesNotThrow(() => {
          s1 = Automerge.change(s1, "del baz", doc => {
            deleted2 = delete doc.baz
          })
        })
        assert.strictEqual(deleted2, true)
      })

      it("should allow the type of a property to be changed", () => {
        s1 = Automerge.change(s1, "set number", doc => (doc.prop = 123))
        assert.strictEqual(s1.prop, 123)
        s1 = Automerge.change(s1, "set string", doc => (doc.prop = "123"))
        assert.strictEqual(s1.prop, "123")
        s1 = Automerge.change(s1, "set null", doc => (doc.prop = null))
        assert.strictEqual(s1.prop, null)
        s1 = Automerge.change(s1, "set bool", doc => (doc.prop = true))
        assert.strictEqual(s1.prop, true)
      })

      it("should require property names to be valid", () => {
        assert.throws(() => {
          Automerge.change(s1, "foo", doc => (doc[""] = "x"))
        }, /must not be an empty string/)
      })

      it("should not allow assignment of unsupported datatypes", () => {
        Automerge.change(s1, doc => {
          assert.throws(() => {
            doc.foo = undefined
          }, /Unsupported type of value: undefined/)
          assert.throws(() => {
            doc.foo = { prop: undefined }
          }, /Unsupported type of value: undefined/)
          assert.throws(() => {
            doc.foo = () => {}
          }, /Unsupported type of value: function/)
          assert.throws(() => {
            doc.foo = Symbol("foo")
          }, /Unsupported type of value: symbol/)
        })
      })
    })

    describe("nested maps", () => {
      it("should assign an objectId to nested maps", () => {
        s1 = Automerge.change(s1, doc => {
          doc.nested = {}
        })
        Automerge.getObjectId(s1.nested)
        assert.strictEqual(
          OPID_PATTERN.test(Automerge.getObjectId(s1.nested)!),
          true
        )
        assert.notEqual(Automerge.getObjectId(s1.nested), "_root")
      })

      it("should handle assignment of a nested property", () => {
        s1 = Automerge.change(s1, "first change", doc => {
          doc.nested = {}
          doc.nested.foo = "bar"
        })
        s1 = Automerge.change(s1, "second change", doc => {
          doc.nested.one = 1
        })
        assert.deepStrictEqual(s1, { nested: { foo: "bar", one: 1 } })
        assert.deepStrictEqual(s1.nested, { foo: "bar", one: 1 })
        assert.strictEqual(s1.nested.foo, "bar")
        assert.strictEqual(s1.nested.one, 1)
      })

      it("should handle assignment of an object literal", () => {
        s1 = Automerge.change(s1, doc => {
          doc.textStyle = { bold: false, fontSize: 12 }
        })
        assert.deepStrictEqual(s1, {
          textStyle: { bold: false, fontSize: 12 },
        })
        assert.deepStrictEqual(s1.textStyle, { bold: false, fontSize: 12 })
        assert.strictEqual(s1.textStyle.bold, false)
        assert.strictEqual(s1.textStyle.fontSize, 12)
      })

      it("should handle assignment of multiple nested properties", () => {
        s1 = Automerge.change(s1, doc => {
          doc.textStyle = { bold: false, fontSize: 12 }
          Object.assign(doc.textStyle, { typeface: "Optima", fontSize: 14 })
        })
        assert.strictEqual(s1.textStyle.typeface, "Optima")
        assert.strictEqual(s1.textStyle.bold, false)
        assert.strictEqual(s1.textStyle.fontSize, 14)
        assert.deepStrictEqual(s1.textStyle, {
          typeface: "Optima",
          bold: false,
          fontSize: 14,
        })
      })

      it("should handle arbitrary-depth nesting", () => {
        s1 = Automerge.change(s1, doc => {
          doc.a = { b: { c: { d: { e: { f: { g: "h" } } } } } }
        })
        s1 = Automerge.change(s1, doc => {
          doc.a.b.c.d.e.f.i = "j"
        })
        assert.deepStrictEqual(s1, {
          a: { b: { c: { d: { e: { f: { g: "h", i: "j" } } } } } },
        })
        assert.strictEqual(s1.a.b.c.d.e.f.g, "h")
        assert.strictEqual(s1.a.b.c.d.e.f.i, "j")
      })

      it("should allow an old object to be replaced with a new one", () => {
        s1 = Automerge.change(s1, "change 1", doc => {
          doc.myPet = { species: "dog", legs: 4, breed: "dachshund" }
        })
        let s2 = Automerge.change(s1, "change 2", doc => {
          doc.myPet = {
            species: "koi",
            variety: "紅白",
            colors: { red: true, white: true, black: false },
          }
        })
        assert.deepStrictEqual(s1.myPet, {
          species: "dog",
          legs: 4,
          breed: "dachshund",
        })
        assert.strictEqual(s1.myPet.breed, "dachshund")
        assert.deepStrictEqual(s2.myPet, {
          species: "koi",
          variety: "紅白",
          colors: { red: true, white: true, black: false },
        })
        // @ts-ignore
        assert.strictEqual(s2.myPet.breed, undefined)
        assert.strictEqual(s2.myPet.variety, "紅白")
      })

      it("should allow fields to be changed between primitive and nested map", () => {
        s1 = Automerge.change(s1, doc => (doc.color = "#ff7f00"))
        assert.strictEqual(s1.color, "#ff7f00")
        s1 = Automerge.change(
          s1,
          doc => (doc.color = { red: 255, green: 127, blue: 0 })
        )
        assert.deepStrictEqual(s1.color, { red: 255, green: 127, blue: 0 })
        s1 = Automerge.change(s1, doc => (doc.color = "#ff7f00"))
        assert.strictEqual(s1.color, "#ff7f00")
      })

      it("should not allow several references to the same map object", () => {
        s1 = Automerge.change(s1, doc => (doc.object = {}))
        assert.throws(() => {
          Automerge.change(s1, doc => {
            doc.x = doc.object
          })
        }, /Cannot create a reference to an existing document object/)
        assert.throws(() => {
          Automerge.change(s1, doc => {
            doc.x = s1.object
          })
        }, /Cannot create a reference to an existing document object/)
        assert.throws(() => {
          Automerge.change(s1, doc => {
            doc.x = {}
            doc.y = doc.x
          })
        }, /Cannot create a reference to an existing document object/)
      })

      it("should not allow object-copying idioms", () => {
        s1 = Automerge.change(s1, doc => {
          doc.items = [
            { id: "id1", name: "one" },
            { id: "id2", name: "two" },
          ]
        })
        // People who have previously worked with immutable state in JavaScript may be tempted
        // to use idioms like this, which don't work well with Automerge -- see e.g.
        // https://github.com/automerge/automerge/issues/260
        assert.throws(() => {
          Automerge.change(s1, doc => {
            doc.items = [...doc.items, { id: "id3", name: "three" }]
          })
        }, /Cannot create a reference to an existing document object/)
      })

      it("should handle deletion of properties within a map", () => {
        s1 = Automerge.change(s1, "set style", doc => {
          doc.textStyle = { typeface: "Optima", bold: false, fontSize: 12 }
        })
        s1 = Automerge.change(s1, "non-bold", doc => delete doc.textStyle.bold)
        assert.strictEqual(s1.textStyle.bold, undefined)
        assert.deepStrictEqual(s1.textStyle, {
          typeface: "Optima",
          fontSize: 12,
        })
      })

      it("should handle deletion of references to a map", () => {
        s1 = Automerge.change(s1, "make rich text doc", doc => {
          Object.assign(doc, {
            title: "Hello",
            textStyle: { typeface: "Optima", fontSize: 12 },
          })
        })
        s1 = Automerge.change(s1, doc => delete doc.textStyle)
        assert.strictEqual(s1.textStyle, undefined)
        assert.deepStrictEqual(s1, { title: "Hello" })
      })

      it("should validate field names", () => {
        s1 = Automerge.change(s1, doc => (doc.nested = {}))
        assert.throws(() => {
          Automerge.change(s1, doc => (doc.nested[""] = "x"))
        }, /must not be an empty string/)
        assert.throws(() => {
          Automerge.change(s1, doc => (doc.nested = { "": "x" }))
        }, /must not be an empty string/)
      })
    })

    describe("lists", () => {
      it("should allow elements to be inserted", () => {
        s1 = Automerge.change(s1, doc => (doc.noodles = []))
        s1 = Automerge.change(s1, doc =>
          doc.noodles.insertAt(0, "udon", "soba")
        )
        s1 = Automerge.change(s1, doc => doc.noodles.insertAt(1, "ramen"))
        assert.deepStrictEqual(s1, { noodles: ["udon", "ramen", "soba"] })
        assert.deepStrictEqual(s1.noodles, ["udon", "ramen", "soba"])
        assert.strictEqual(s1.noodles[0], "udon")
        assert.strictEqual(s1.noodles[1], "ramen")
        assert.strictEqual(s1.noodles[2], "soba")
        assert.strictEqual(s1.noodles.length, 3)
      })

      it("should handle assignment of a list literal", () => {
        s1 = Automerge.change(
          s1,
          doc => (doc.noodles = ["udon", "ramen", "soba"])
        )
        assert.deepStrictEqual(s1, { noodles: ["udon", "ramen", "soba"] })
        assert.deepStrictEqual(s1.noodles, ["udon", "ramen", "soba"])
        assert.strictEqual(s1.noodles[0], "udon")
        assert.strictEqual(s1.noodles[1], "ramen")
        assert.strictEqual(s1.noodles[2], "soba")
        assert.strictEqual(s1.noodles[3], undefined)
        assert.strictEqual(s1.noodles.length, 3)
      })

      it("should only allow numeric indexes", () => {
        s1 = Automerge.change(
          s1,
          doc => (doc.noodles = ["udon", "ramen", "soba"])
        )
        s1 = Automerge.change(s1, doc => (doc.noodles[1] = "Ramen!"))
        assert.strictEqual(s1.noodles[1], "Ramen!")
        s1 = Automerge.change(s1, doc => (doc.noodles["1"] = "RAMEN!!!"))
        assert.strictEqual(s1.noodles[1], "RAMEN!!!")
        assert.throws(() => {
          Automerge.change(s1, doc => (doc.noodles.favourite = "udon"))
        }, /list index must be a number/)
        assert.throws(() => {
          Automerge.change(s1, doc => (doc.noodles[""] = "udon"))
        }, /list index must be a number/)
        assert.throws(() => {
          Automerge.change(s1, doc => (doc.noodles["1e6"] = "udon"))
        }, /list index must be a number/)
      })

      it("should handle deletion of list elements", () => {
        s1 = Automerge.change(
          s1,
          doc => (doc.noodles = ["udon", "ramen", "soba"])
        )
        s1 = Automerge.change(s1, doc => delete doc.noodles[1])
        assert.deepStrictEqual(s1.noodles, ["udon", "soba"])
        s1 = Automerge.change(s1, doc => doc.noodles.deleteAt(1))
        assert.deepStrictEqual(s1.noodles, ["udon"])
        assert.strictEqual(s1.noodles[0], "udon")
        assert.strictEqual(s1.noodles[1], undefined)
        assert.strictEqual(s1.noodles[2], undefined)
        assert.strictEqual(s1.noodles.length, 1)
      })

      it("should handle assignment of individual list indexes", () => {
        s1 = Automerge.change(
          s1,
          doc => (doc.japaneseFood = ["udon", "ramen", "soba"])
        )
        s1 = Automerge.change(s1, doc => (doc.japaneseFood[1] = "sushi"))
        assert.deepStrictEqual(s1.japaneseFood, ["udon", "sushi", "soba"])
        assert.strictEqual(s1.japaneseFood[0], "udon")
        assert.strictEqual(s1.japaneseFood[1], "sushi")
        assert.strictEqual(s1.japaneseFood[2], "soba")
        assert.strictEqual(s1.japaneseFood[3], undefined)
        assert.strictEqual(s1.japaneseFood.length, 3)
      })

      it("concurrent edits insert in reverse actorid order if counters equal", () => {
        s1 = Automerge.init("aaaa")
        s2 = Automerge.init("bbbb")
        s1 = Automerge.change(s1, doc => (doc.list = []))
        s2 = Automerge.merge(s2, s1)
        s1 = Automerge.change(s1, doc => doc.list.splice(0, 0, "2@aaaa"))
        s2 = Automerge.change(s2, doc => doc.list.splice(0, 0, "2@bbbb"))
        s2 = Automerge.merge(s2, s1)
        assert.deepStrictEqual(Automerge.toJS(s2).list, ["2@bbbb", "2@aaaa"])
      })

      it("concurrent edits insert in reverse counter order if different", () => {
        s1 = Automerge.init("aaaa")
        s2 = Automerge.init("bbbb")
        s1 = Automerge.change(s1, doc => (doc.list = []))
        s2 = Automerge.merge(s2, s1)
        s1 = Automerge.change(s1, doc => doc.list.splice(0, 0, "2@aaaa"))
        s2 = Automerge.change(s2, doc => (doc.foo = "2@bbbb"))
        s2 = Automerge.change(s2, doc => doc.list.splice(0, 0, "3@bbbb"))
        s2 = Automerge.merge(s2, s1)
        assert.deepStrictEqual(s2.list, ["3@bbbb", "2@aaaa"])
      })

      it("should treat out-by-one assignment as insertion", () => {
        s1 = Automerge.change(s1, doc => (doc.japaneseFood = ["udon"]))
        s1 = Automerge.change(s1, doc => (doc.japaneseFood[1] = "sushi"))
        assert.deepStrictEqual(s1.japaneseFood, ["udon", "sushi"])
        assert.strictEqual(s1.japaneseFood[0], "udon")
        assert.strictEqual(s1.japaneseFood[1], "sushi")
        assert.strictEqual(s1.japaneseFood[2], undefined)
        assert.strictEqual(s1.japaneseFood.length, 2)
      })

      it("should not allow out-of-range assignment", () => {
        s1 = Automerge.change(s1, doc => (doc.japaneseFood = ["udon"]))
        assert.throws(() => {
          Automerge.change(s1, doc => (doc.japaneseFood[4] = "ramen"))
        }, /is out of bounds/)
      })

      it("should allow bulk assignment of multiple list indexes", () => {
        s1 = Automerge.change(
          s1,
          doc => (doc.noodles = ["udon", "ramen", "soba"])
        )
        s1 = Automerge.change(s1, doc =>
          Object.assign(doc.noodles, { 0: "うどん", 2: "そば" })
        )
        assert.deepStrictEqual(s1.noodles, ["うどん", "ramen", "そば"])
        assert.strictEqual(s1.noodles[0], "うどん")
        assert.strictEqual(s1.noodles[1], "ramen")
        assert.strictEqual(s1.noodles[2], "そば")
        assert.strictEqual(s1.noodles.length, 3)
      })

      it("should handle nested objects", () => {
        s1 = Automerge.change(
          s1,
          doc =>
            (doc.noodles = [{ type: "ramen", dishes: ["tonkotsu", "shoyu"] }])
        )
        s1 = Automerge.change(s1, doc =>
          doc.noodles.push({ type: "udon", dishes: ["tempura udon"] })
        )
        s1 = Automerge.change(s1, doc => doc.noodles[0].dishes.push("miso"))
        assert.deepStrictEqual(s1, {
          noodles: [
            { type: "ramen", dishes: ["tonkotsu", "shoyu", "miso"] },
            { type: "udon", dishes: ["tempura udon"] },
          ],
        })
        assert.deepStrictEqual(s1.noodles[0], {
          type: "ramen",
          dishes: ["tonkotsu", "shoyu", "miso"],
        })
        assert.deepStrictEqual(s1.noodles[1], {
          type: "udon",
          dishes: ["tempura udon"],
        })
      })

      it("should handle nested lists", () => {
        s1 = Automerge.change(
          s1,
          doc => (doc.noodleMatrix = [["ramen", "tonkotsu", "shoyu"]])
        )
        s1 = Automerge.change(s1, doc =>
          doc.noodleMatrix.push(["udon", "tempura udon"])
        )
        s1 = Automerge.change(s1, doc => doc.noodleMatrix[0].push("miso"))
        assert.deepStrictEqual(s1.noodleMatrix, [
          ["ramen", "tonkotsu", "shoyu", "miso"],
          ["udon", "tempura udon"],
        ])
        assert.deepStrictEqual(s1.noodleMatrix[0], [
          "ramen",
          "tonkotsu",
          "shoyu",
          "miso",
        ])
        assert.deepStrictEqual(s1.noodleMatrix[1], ["udon", "tempura udon"])
      })

      it("should handle deep nesting", () => {
        s1 = Automerge.change(
          s1,
          doc =>
            (doc.nesting = {
              maps: { m1: { m2: { foo: "bar", baz: {} }, m2a: {} } },
              lists: [
                [1, 2, 3],
                [[3, 4, 5, [6]], 7],
              ],
              mapsinlists: [{ foo: "bar" }, [{ bar: "baz" }]],
              listsinmaps: { foo: [1, 2, 3], bar: [[{ baz: "123" }]] },
            })
        )
        s1 = Automerge.change(s1, doc => {
          doc.nesting.maps.m1a = "123"
          doc.nesting.maps.m1.m2.baz.xxx = "123"
          delete doc.nesting.maps.m1.m2a
          doc.nesting.lists.shift()
          doc.nesting.lists[0][0].pop()
          doc.nesting.lists[0][0].push(100)
          doc.nesting.mapsinlists[0].foo = "baz"
          doc.nesting.mapsinlists[1][0].foo = "bar"
          delete doc.nesting.mapsinlists[1]
          doc.nesting.listsinmaps.foo.push(4)
          doc.nesting.listsinmaps.bar[0][0].baz = "456"
          delete doc.nesting.listsinmaps.bar
        })
        assert.deepStrictEqual(s1, {
          nesting: {
            maps: {
              m1: { m2: { foo: "bar", baz: { xxx: "123" } } },
              m1a: "123",
            },
            lists: [[[3, 4, 5, 100], 7]],
            mapsinlists: [{ foo: "baz" }],
            listsinmaps: { foo: [1, 2, 3, 4] },
          },
        })
      })

      it("should handle replacement of the entire list", () => {
        s1 = Automerge.change(
          s1,
          doc => (doc.noodles = ["udon", "soba", "ramen"])
        )
        s1 = Automerge.change(
          s1,
          doc => (doc.japaneseNoodles = doc.noodles.slice())
        )
        s1 = Automerge.change(s1, doc => (doc.noodles = ["wonton", "pho"]))
        assert.deepStrictEqual(s1, {
          noodles: ["wonton", "pho"],
          japaneseNoodles: ["udon", "soba", "ramen"],
        })
        assert.deepStrictEqual(s1.noodles, ["wonton", "pho"])
        assert.strictEqual(s1.noodles[0], "wonton")
        assert.strictEqual(s1.noodles[1], "pho")
        assert.strictEqual(s1.noodles[2], undefined)
        assert.strictEqual(s1.noodles.length, 2)
      })

      it("should allow assignment to change the type of a list element", () => {
        s1 = Automerge.change(
          s1,
          doc => (doc.noodles = ["udon", "soba", "ramen"])
        )
        assert.deepStrictEqual(s1.noodles, ["udon", "soba", "ramen"])
        s1 = Automerge.change(
          s1,
          doc => (doc.noodles[1] = { type: "soba", options: ["hot", "cold"] })
        )
        assert.deepStrictEqual(s1.noodles, [
          "udon",
          { type: "soba", options: ["hot", "cold"] },
          "ramen",
        ])
        s1 = Automerge.change(
          s1,
          doc => (doc.noodles[1] = ["hot soba", "cold soba"])
        )
        assert.deepStrictEqual(s1.noodles, [
          "udon",
          ["hot soba", "cold soba"],
          "ramen",
        ])
        s1 = Automerge.change(s1, doc => (doc.noodles[1] = "soba is the best"))
        assert.deepStrictEqual(s1.noodles, [
          "udon",
          "soba is the best",
          "ramen",
        ])
      })

      it("should allow list creation and assignment in the same change callback", () => {
        s1 = Automerge.change(Automerge.init(), doc => {
          doc.letters = ["a", "b", "c"]
          doc.letters[1] = "d"
        })
        assert.strictEqual(s1.letters[1], "d")
      })

      it("should allow adding and removing list elements in the same change callback", () => {
        let s1 = Automerge.change(
          Automerge.init<{ noodles: Array<string> }>(),
          // @ts-ignore
          doc => (doc.noodles = [])
        )
        s1 = Automerge.change(s1, doc => {
          doc.noodles.push("udon")
          // @ts-ignore
          doc.noodles.deleteAt(0)
        })
        assert.deepStrictEqual(s1, { noodles: [] })
        // do the add-remove cycle twice, test for #151 (https://github.com/automerge/automerge/issues/151)
        s1 = Automerge.change(s1, doc => {
          // @ts-ignore
          doc.noodles.push("soba")
          // @ts-ignore
          doc.noodles.deleteAt(0)
        })
        assert.deepStrictEqual(s1, { noodles: [] })
      })

      it("should handle arbitrary-depth nesting", () => {
        s1 = Automerge.change(
          s1,
          doc => (doc.maze = [[[[[[[["noodles", ["here"]]]]]]]]])
        )
        s1 = Automerge.change(s1, doc =>
          doc.maze[0][0][0][0][0][0][0][1].unshift("found")
        )
        assert.deepStrictEqual(s1.maze, [
          [[[[[[["noodles", ["found", "here"]]]]]]]],
        ])
        assert.deepStrictEqual(s1.maze[0][0][0][0][0][0][0][1][1], "here")
        s2 = Automerge.load(Automerge.save(s1))
        assert.deepStrictEqual(s1, s2)
      })

      it("should not allow several references to the same list object", () => {
        s1 = Automerge.change(s1, doc => (doc.list = []))
        assert.throws(() => {
          Automerge.change(s1, doc => {
            doc.x = doc.list
          })
        }, /Cannot create a reference to an existing document object/)
        assert.throws(() => {
          Automerge.change(s1, doc => {
            doc.x = s1.list
          })
        }, /Cannot create a reference to an existing document object/)
        assert.throws(() => {
          Automerge.change(s1, doc => {
            doc.x = []
            doc.y = doc.x
          })
        }, /Cannot create a reference to an existing document object/)
      })
    })

    describe("counters", () => {
      // counter
      it("should allow deleting counters from maps", () => {
        const s1 = Automerge.change(
          Automerge.init<any>(),
          doc => (doc.birds = { wrens: new Automerge.Counter(1) })
        )
        const s2 = Automerge.change(s1, doc => doc.birds.wrens.increment(2))
        const s3 = Automerge.change(s2, doc => delete doc.birds.wrens)
        assert.deepStrictEqual(s2, {
          birds: { wrens: new Automerge.Counter(3) },
        })
        assert.deepStrictEqual(s3, { birds: {} })
      })

      // counter
      /*
      it('should not allow deleting counters from lists', () => {
        const s1 = Automerge.change(Automerge.init(), doc => doc.recordings = [new Automerge.Counter(1)])
        const s2 = Automerge.change(s1, doc => doc.recordings[0].increment(2))
        assert.deepStrictEqual(s2, {recordings: [new Automerge.Counter(3)]})
        assert.throws(() => { Automerge.change(s2, doc => doc.recordings.deleteAt(0)) }, /Unsupported operation/)
      })
      */
    })
  })

  describe("concurrent use", () => {
    let s1: Automerge.Doc<any>,
      s2: Automerge.Doc<any>,
      s3: Automerge.Doc<any>,
      s4: Automerge.Doc<any>
    beforeEach(() => {
      s1 = Automerge.init<any>()
      s2 = Automerge.init<any>()
      s3 = Automerge.init<any>()
      s4 = Automerge.init<any>()
    })

    it("should merge concurrent updates of different properties", () => {
      s1 = Automerge.change(s1, doc => (doc.foo = "bar"))
      s2 = Automerge.change(s2, doc => (doc.hello = "world"))
      s3 = Automerge.merge(s1, s2)
      assert.strictEqual(s3.foo, "bar")
      assert.strictEqual(s3.hello, "world")
      assert.deepStrictEqual(s3, { foo: "bar", hello: "world" })
      assert.strictEqual(Automerge.getConflicts(s3, "foo"), undefined)
      assert.strictEqual(Automerge.getConflicts(s3, "hello"), undefined)
      s4 = Automerge.load(Automerge.save(s3))
      assert.deepEqual(s3, s4)
    })

    it("should add concurrent increments of the same property", () => {
      s1 = Automerge.change(s1, doc => (doc.counter = new Automerge.Counter()))
      s2 = Automerge.merge(s2, s1)
      s1 = Automerge.change(s1, doc => doc.counter.increment())
      s2 = Automerge.change(s2, doc => doc.counter.increment(2))
      s3 = Automerge.merge(s1, s2)
      assert.strictEqual(s1.counter.value, 1)
      assert.strictEqual(s2.counter.value, 2)
      assert.strictEqual(s3.counter.value, 3)
      assert.strictEqual(Automerge.getConflicts(s3, "counter"), undefined)
      s4 = Automerge.load(Automerge.save(s3))
      assert.deepEqual(s3, s4)
    })

    it("should add increments only to the values they precede", () => {
      s1 = Automerge.change(s1, doc => (doc.counter = new Automerge.Counter(0)))
      s1 = Automerge.change(s1, doc => doc.counter.increment())
      s2 = Automerge.change(
        s2,
        doc => (doc.counter = new Automerge.Counter(100))
      )
      s2 = Automerge.change(s2, doc => doc.counter.increment(3))
      s3 = Automerge.merge(s1, s2)
      if (Automerge.getActorId(s1) > Automerge.getActorId(s2)) {
        assert.deepStrictEqual(s3, { counter: new Automerge.Counter(1) })
      } else {
        assert.deepStrictEqual(s3, { counter: new Automerge.Counter(103) })
      }
      assert.deepStrictEqual(Automerge.getConflicts(s3, "counter"), {
        [`1@${Automerge.getActorId(s1)}`]: new Automerge.Counter(1),
        [`1@${Automerge.getActorId(s2)}`]: new Automerge.Counter(103),
      })
      s4 = Automerge.load(Automerge.save(s3))
      assert.deepEqual(s3, s4)
    })

    it("should detect concurrent updates of the same field", () => {
      s1 = Automerge.change(s1, doc => (doc.field = "one"))
      s2 = Automerge.change(s2, doc => (doc.field = "two"))
      s3 = Automerge.merge(s1, s2)
      if (Automerge.getActorId(s1) > Automerge.getActorId(s2)) {
        assert.deepStrictEqual(s3, { field: "one" })
      } else {
        assert.deepStrictEqual(s3, { field: "two" })
      }
      assert.deepStrictEqual(Automerge.getConflicts(s3, "field"), {
        [`1@${Automerge.getActorId(s1)}`]: "one",
        [`1@${Automerge.getActorId(s2)}`]: "two",
      })
    })

    it("should detect concurrent updates of the same list element", () => {
      s1 = Automerge.change(s1, doc => (doc.birds = ["finch"]))
      s2 = Automerge.merge(s2, s1)
      s1 = Automerge.change(s1, doc => (doc.birds[0] = "greenfinch"))
      s2 = Automerge.change(s2, doc => (doc.birds[0] = "goldfinch_"))
      s3 = Automerge.merge(s1, s2)
      if (Automerge.getActorId(s1) > Automerge.getActorId(s2)) {
        assert.deepStrictEqual(s3.birds, ["greenfinch"])
      } else {
        assert.deepStrictEqual(s3.birds, ["goldfinch_"])
      }
      assert.deepStrictEqual(Automerge.getConflicts(s3.birds, 0), {
        [`8@${Automerge.getActorId(s1)}`]: "greenfinch",
        [`8@${Automerge.getActorId(s2)}`]: "goldfinch_",
      })
    })

    it("should handle assignment conflicts of different types", () => {
      s1 = Automerge.change(s1, doc => (doc.field = "string"))
      s2 = Automerge.change(s2, doc => (doc.field = ["list"]))
      s3 = Automerge.change(s3, doc => (doc.field = { thing: "map" }))
      s1 = Automerge.merge(Automerge.merge(s1, s2), s3)
      assertEqualsOneOf(s1.field, "string", ["list"], { thing: "map" })
      assert.deepStrictEqual(Automerge.getConflicts(s1, "field"), {
        [`1@${Automerge.getActorId(s1)}`]: "string",
        [`1@${Automerge.getActorId(s2)}`]: ["list"],
        [`1@${Automerge.getActorId(s3)}`]: { thing: "map" },
      })
    })

    it("should handle changes within a conflicting map field", () => {
      s1 = Automerge.change(s1, doc => (doc.field = "string"))
      s2 = Automerge.change(s2, doc => (doc.field = {}))
      s2 = Automerge.change(s2, doc => (doc.field.innerKey = 42))
      s3 = Automerge.merge(s1, s2)
      assertEqualsOneOf(s3.field, "string", { innerKey: 42 })
      assert.deepStrictEqual(Automerge.getConflicts(s3, "field"), {
        [`1@${Automerge.getActorId(s1)}`]: "string",
        [`1@${Automerge.getActorId(s2)}`]: { innerKey: 42 },
      })
    })

    it("should handle changes within a conflicting list element", () => {
      s1 = Automerge.change(s1, doc => (doc.list = ["hello"]))
      s2 = Automerge.merge(s2, s1)
      s1 = Automerge.change(s1, doc => (doc.list[0] = { map1: true }))
      s1 = Automerge.change(s1, doc => (doc.list[0].key = 1))
      s2 = Automerge.change(s2, doc => (doc.list[0] = { map2: true }))
      s2 = Automerge.change(s2, doc => (doc.list[0].key = 2))
      s3 = Automerge.merge(s1, s2)
      if (Automerge.getActorId(s1) > Automerge.getActorId(s2)) {
        assert.deepStrictEqual(s3.list, [{ map1: true, key: 1 }])
      } else {
        assert.deepStrictEqual(s3.list, [{ map2: true, key: 2 }])
      }
      assert.deepStrictEqual(Automerge.getConflicts<any>(s3.list, 0), {
        [`8@${Automerge.getActorId(s1)}`]: { map1: true, key: 1 },
        [`8@${Automerge.getActorId(s2)}`]: { map2: true, key: 2 },
      })
    })

    it("should not merge concurrently assigned nested maps", () => {
      s1 = Automerge.change(s1, doc => (doc.config = { background: "blue" }))
      s2 = Automerge.change(s2, doc => (doc.config = { logo_url: "logo.png" }))
      s3 = Automerge.merge(s1, s2)
      assertEqualsOneOf(
        s3.config,
        { background: "blue" },
        { logo_url: "logo.png" }
      )
      assert.deepStrictEqual(Automerge.getConflicts(s3, "config"), {
        [`1@${Automerge.getActorId(s1)}`]: { background: "blue" },
        [`1@${Automerge.getActorId(s2)}`]: { logo_url: "logo.png" },
      })
    })

    it("should clear conflicts after assigning a new value", () => {
      s1 = Automerge.change(s1, doc => (doc.field = "one"))
      s2 = Automerge.change(s2, doc => (doc.field = "two"))
      s3 = Automerge.merge(s1, s2)
      s3 = Automerge.change(s3, doc => (doc.field = "three"))
      assert.deepStrictEqual(s3, { field: "three" })
      assert.strictEqual(Automerge.getConflicts(s3, "field"), undefined)
      s2 = Automerge.merge(s2, s3)
      assert.deepStrictEqual(s2, { field: "three" })
      assert.strictEqual(Automerge.getConflicts(s2, "field"), undefined)
    })

    it("should handle concurrent insertions at different list positions", () => {
      s1 = Automerge.change(s1, doc => (doc.list = ["one", "three"]))
      s2 = Automerge.merge(s2, s1)
      s1 = Automerge.change(s1, doc => doc.list.splice(1, 0, "two"))
      s2 = Automerge.change(s2, doc => doc.list.push("four"))
      s3 = Automerge.merge(s1, s2)
      assert.deepStrictEqual(s3, { list: ["one", "two", "three", "four"] })
      assert.strictEqual(Automerge.getConflicts(s3, "list"), undefined)
    })

    it("should handle concurrent insertions at the same list position", () => {
      s1 = Automerge.change(s1, doc => (doc.birds = ["parakeet"]))
      s2 = Automerge.merge(s2, s1)
      s1 = Automerge.change(s1, doc => doc.birds.push("starling"))
      s2 = Automerge.change(s2, doc => doc.birds.push("chaffinch"))
      s3 = Automerge.merge(s1, s2)
      assertEqualsOneOf(
        s3.birds,
        ["parakeet", "starling", "chaffinch"],
        ["parakeet", "chaffinch", "starling"]
      )
      s2 = Automerge.merge(s2, s3)
      assert.deepStrictEqual(s2, s3)
    })

    it("should handle concurrent assignment and deletion of a map entry", () => {
      // Add-wins semantics
      s1 = Automerge.change(s1, doc => (doc.bestBird = "robin"))
      s2 = Automerge.merge(s2, s1)
      s1 = Automerge.change(s1, doc => delete doc.bestBird)
      s2 = Automerge.change(s2, doc => (doc.bestBird = "magpie"))
      s3 = Automerge.merge(s1, s2)
      assert.deepStrictEqual(s1, {})
      assert.deepStrictEqual(s2, { bestBird: "magpie" })
      assert.deepStrictEqual(s3, { bestBird: "magpie" })
      assert.strictEqual(Automerge.getConflicts(s3, "bestBird"), undefined)
    })

    it("should handle concurrent assignment and deletion of a list element", () => {
      // Concurrent assignment ressurects a deleted list element. Perhaps a little
      // surprising, but consistent with add-wins semantics of maps (see test above)
      s1 = Automerge.change(
        s1,
        doc => (doc.birds = ["blackbird", "thrush", "goldfinch"])
      )
      s2 = Automerge.merge(s2, s1)
      s1 = Automerge.change(s1, doc => (doc.birds[1] = "starling"))
      s2 = Automerge.change(s2, doc => doc.birds.splice(1, 1))
      s3 = Automerge.merge(s1, s2)
      assert.deepStrictEqual(s1.birds, ["blackbird", "starling", "goldfinch"])
      assert.deepStrictEqual(s2.birds, ["blackbird", "goldfinch"])
      assert.deepStrictEqual(s3.birds, ["blackbird", "starling", "goldfinch"])
      s4 = Automerge.load(Automerge.save(s3))
      assert.deepStrictEqual(s3, s4)
    })

    it("should handle insertion after a deleted list element", () => {
      s1 = Automerge.change(
        s1,
        doc => (doc.birds = ["blackbird", "thrush", "goldfinch"])
      )
      s2 = Automerge.merge(s2, s1)
      s1 = Automerge.change(s1, doc => doc.birds.splice(1, 2))
      s2 = Automerge.change(s2, doc => doc.birds.splice(2, 0, "starling"))
      s3 = Automerge.merge(s1, s2)
      assert.deepStrictEqual(s3, { birds: ["blackbird", "starling"] })
      assert.deepStrictEqual(Automerge.merge(s2, s3), {
        birds: ["blackbird", "starling"],
      })
    })

    it("should handle concurrent deletion of the same element", () => {
      s1 = Automerge.change(
        s1,
        doc => (doc.birds = ["albatross", "buzzard", "cormorant"])
      )
      s2 = Automerge.merge(s2, s1)
      s1 = Automerge.change(s1, doc => doc.birds.deleteAt(1)) // buzzard
      s2 = Automerge.change(s2, doc => doc.birds.deleteAt(1)) // buzzard
      s3 = Automerge.merge(s1, s2)
      assert.deepStrictEqual(s3.birds, ["albatross", "cormorant"])
    })

    it("should handle concurrent deletion of different elements", () => {
      s1 = Automerge.change(
        s1,
        doc => (doc.birds = ["albatross", "buzzard", "cormorant"])
      )
      s2 = Automerge.merge(s2, s1)
      s1 = Automerge.change(s1, doc => doc.birds.deleteAt(0)) // albatross
      s2 = Automerge.change(s2, doc => doc.birds.deleteAt(1)) // buzzard
      s3 = Automerge.merge(s1, s2)
      assert.deepStrictEqual(s3.birds, ["cormorant"])
    })

    it("should handle concurrent updates at different levels of the tree", () => {
      // A delete higher up in the tree overrides an update in a subtree
      s1 = Automerge.change(
        s1,
        doc =>
          (doc.animals = {
            birds: { pink: "flamingo", black: "starling" },
            mammals: ["badger"],
          })
      )
      s2 = Automerge.merge(s2, s1)
      s1 = Automerge.change(s1, doc => (doc.animals.birds.brown = "sparrow"))
      s2 = Automerge.change(s2, doc => delete doc.animals.birds)
      s3 = Automerge.merge(s1, s2)
      assert.deepStrictEqual(s1.animals, {
        birds: {
          pink: "flamingo",
          brown: "sparrow",
          black: "starling",
        },
        mammals: ["badger"],
      })
      assert.deepStrictEqual(s2.animals, { mammals: ["badger"] })
      assert.deepStrictEqual(s3.animals, { mammals: ["badger"] })
    })

    it("should handle updates of concurrently deleted objects", () => {
      s1 = Automerge.change(
        s1,
        doc => (doc.birds = { blackbird: { feathers: "black" } })
      )
      s2 = Automerge.merge(s2, s1)
      s1 = Automerge.change(s1, doc => delete doc.birds.blackbird)
      s2 = Automerge.change(s2, doc => (doc.birds.blackbird.beak = "orange"))
      s3 = Automerge.merge(s1, s2)
      assert.deepStrictEqual(s1, { birds: {} })
    })

    it("should not interleave sequence insertions at the same position", () => {
      s1 = Automerge.change(s1, doc => (doc.wisdom = []))
      s2 = Automerge.merge(s2, s1)
      s1 = Automerge.change(s1, doc =>
        doc.wisdom.push("to", "be", "is", "to", "do")
      )
      s2 = Automerge.change(s2, doc =>
        doc.wisdom.push("to", "do", "is", "to", "be")
      )
      s3 = Automerge.merge(s1, s2)
      assertEqualsOneOf(
        s3.wisdom,
        ["to", "be", "is", "to", "do", "to", "do", "is", "to", "be"],
        ["to", "do", "is", "to", "be", "to", "be", "is", "to", "do"]
      )
      // In case you're wondering: http://quoteinvestigator.com/2013/09/16/do-be-do/
    })

    describe("multiple insertions at the same list position", () => {
      it("should handle insertion by greater actor ID", () => {
        s1 = Automerge.init("aaaa")
        s2 = Automerge.init("bbbb")
        s1 = Automerge.change(s1, doc => (doc.list = ["two"]))
        s2 = Automerge.merge(s2, s1)
        s2 = Automerge.change(s2, doc => doc.list.splice(0, 0, "one"))
        assert.deepStrictEqual(s2.list, ["one", "two"])
      })

      it("should handle insertion by lesser actor ID", () => {
        s1 = Automerge.init("bbbb")
        s2 = Automerge.init("aaaa")
        s1 = Automerge.change(s1, doc => (doc.list = ["two"]))
        s2 = Automerge.merge(s2, s1)
        s2 = Automerge.change(s2, doc => doc.list.splice(0, 0, "one"))
        assert.deepStrictEqual(s2.list, ["one", "two"])
      })

      it("should handle insertion regardless of actor ID", () => {
        s1 = Automerge.change(s1, doc => (doc.list = ["two"]))
        s2 = Automerge.merge(s2, s1)
        s2 = Automerge.change(s2, doc => doc.list.splice(0, 0, "one"))
        assert.deepStrictEqual(s2.list, ["one", "two"])
      })

      it("should make insertion order consistent with causality", () => {
        s1 = Automerge.change(s1, doc => (doc.list = ["four"]))
        s2 = Automerge.merge(s2, s1)
        s2 = Automerge.change(s2, doc => doc.list.unshift("three"))
        s1 = Automerge.merge(s1, s2)
        s1 = Automerge.change(s1, doc => doc.list.unshift("two"))
        s2 = Automerge.merge(s2, s1)
        s2 = Automerge.change(s2, doc => doc.list.unshift("one"))
        assert.deepStrictEqual(s2.list, ["one", "two", "three", "four"])
      })
    })
  })

  describe("saving and loading", () => {
    it("should save and restore an empty document", () => {
      let s = Automerge.load(Automerge.save(Automerge.init()))
      assert.deepStrictEqual(s, {})
    })

    it("should generate a new random actor ID", () => {
      let s1 = Automerge.init()
      let s2 = Automerge.load(Automerge.save(s1))
      assert.strictEqual(
        UUID_PATTERN.test(Automerge.getActorId(s1).toString()),
        true
      )
      assert.strictEqual(
        UUID_PATTERN.test(Automerge.getActorId(s2).toString()),
        true
      )
      assert.notEqual(Automerge.getActorId(s1), Automerge.getActorId(s2))
    })

    it("should allow a custom actor ID to be set", () => {
      let s = Automerge.load(Automerge.save(Automerge.init()), "333333")
      assert.strictEqual(Automerge.getActorId(s), "333333")
    })

    it("should reconstitute complex datatypes", () => {
      let s1 = Automerge.change(
        Automerge.init<any>(),
        doc => (doc.todos = [{ title: "water plants", done: false }])
      )
      let s2 = Automerge.load(Automerge.save(s1))
      assert.deepStrictEqual(s2, {
        todos: [{ title: "water plants", done: false }],
      })
    })

    it("should save and load maps with @ symbols in the keys", () => {
      let s1 = Automerge.change(
        Automerge.init<any>(),
        doc => (doc["123@4567"] = "hello")
      )
      let s2 = Automerge.load(Automerge.save(s1))
      assert.deepStrictEqual(s2, { "123@4567": "hello" })
    })

    it("should reconstitute conflicts", () => {
      let s1 = Automerge.change(
        Automerge.init<any>("111111"),
        doc => (doc.x = 3)
      )
      let s2 = Automerge.change(
        Automerge.init<any>("222222"),
        doc => (doc.x = 5)
      )
      s1 = Automerge.merge(s1, s2)
      let s3 = Automerge.load<any>(Automerge.save(s1))
      assert.strictEqual(s1.x, 5)
      assert.strictEqual(s3.x, 5)
      assert.deepStrictEqual(Automerge.getConflicts(s1, "x"), {
        "1@111111": 3,
        "1@222222": 5,
      })
      assert.deepStrictEqual(Automerge.getConflicts(s3, "x"), {
        "1@111111": 3,
        "1@222222": 5,
      })
    })

    it("should reconstitute element ID counters", () => {
      const s1 = Automerge.init<any>("01234567")
      const s2 = Automerge.change(s1, doc => (doc.list = ["a"]))
      const listId = Automerge.getObjectId(s2.list)
      const changes12 = Automerge.getAllChanges(s2).map(Automerge.decodeChange)
      assert.deepStrictEqual(changes12, [
        {
          hash: changes12[0].hash,
          actor: "01234567",
          seq: 1,
          startOp: 1,
          time: changes12[0].time,
          message: null,
          deps: [],
          ops: [
            { obj: "_root", action: "makeList", key: "list", pred: [] },
            {
              obj: listId,
              action: "makeText",
              elemId: "_head",
              insert: true,
              pred: [],
            },
            {
              obj: "2@01234567",
              action: "set",
              elemId: "_head",
              insert: true,
              value: "a",
              pred: [],
            },
          ],
        },
      ])
      const s3 = Automerge.change(s2, doc => doc.list.deleteAt(0))
      const s4 = Automerge.load<any>(Automerge.save(s3), "01234567")
      const s5 = Automerge.change(s4, doc => doc.list.push("b"))
      const changes45 = Automerge.getAllChanges(s5).map(Automerge.decodeChange)
      assert.deepStrictEqual(s5, { list: ["b"] })
      assert.deepStrictEqual(changes45[2], {
        hash: changes45[2].hash,
        actor: "01234567",
        seq: 3,
        startOp: 5,
        time: changes45[2].time,
        message: null,
        deps: [changes45[1].hash],
        ops: [
          {
            obj: listId,
            action: "makeText",
            elemId: "_head",
            insert: true,
            pred: [],
          },
          {
            obj: "5@01234567",
            action: "set",
            elemId: "_head",
            insert: true,
            value: "b",
            pred: [],
          },
        ],
      })
    })

    it("should allow a reloaded list to be mutated", () => {
      let doc = Automerge.change(Automerge.init<any>(), doc => (doc.foo = []))
      doc = Automerge.load(Automerge.save(doc))
      doc = Automerge.change(doc, "add", doc => doc.foo.push(1))
      doc = Automerge.load(Automerge.save(doc))
      assert.deepStrictEqual(doc.foo, [1])
    })

    it("should reload a document containing deflated columns", () => {
      // In this test, the keyCtr column is long enough for deflate compression to kick in, but the
      // keyStr column is short. Thus, the deflate bit gets set for keyCtr but not for keyStr.
      // When checking whether the columns appear in ascending order, we must ignore the deflate bit.
      let doc = Automerge.change(Automerge.init<any>(), doc => {
        doc.list = []
        for (let i = 0; i < 200; i++)
          doc.list.insertAt(Math.floor(Math.random() * i), "a")
      })
      Automerge.load<any>(Automerge.save(doc))
      let expected: Array<string> = []
      for (let i = 0; i < 200; i++) expected.push("a")
      assert.deepStrictEqual(doc, { list: expected })
    })

    it.skip("should call patchCallback if supplied to load", () => {
      const s1 = Automerge.change(
        Automerge.init<any>(),
        doc => (doc.birds = ["Goldfinch"])
      )
      const s2 = Automerge.change(s1, doc => doc.birds.push("Chaffinch"))
      const callbacks: Array<any> = [],
        actor = Automerge.getActorId(s1)
      const reloaded = Automerge.load<any>(Automerge.save(s2), {
        patchCallback(patch, before, after) {
          callbacks.push({ patch, before, after })
        },
      })
      assert.strictEqual(callbacks.length, 1)
      assert.deepStrictEqual(callbacks[0].patch, {
        maxOp: 3,
        deps: [decodeChange(Automerge.getAllChanges(s2)[1]).hash],
        clock: { [actor]: 2 },
        pendingChanges: 0,
        diffs: {
          objectId: "_root",
          type: "map",
          props: {
            birds: {
              [`1@${actor}`]: {
                objectId: `1@${actor}`,
                type: "list",
                edits: [
                  {
                    action: "multi-insert",
                    index: 0,
                    elemId: `2@${actor}`,
                    values: ["Goldfinch", "Chaffinch"],
                  },
                ],
              },
            },
          },
        },
      })
      assert.deepStrictEqual(callbacks[0].before, {})
      assert.strictEqual(callbacks[0].after, reloaded)
      assert.strictEqual(callbacks[0].local, false)
    })
  })

  describe("history API", () => {
    it("should return an empty history for an empty document", () => {
      assert.deepStrictEqual(Automerge.getHistory(Automerge.init()), [])
    })

    it("should make past document states accessible", () => {
      let s = Automerge.init<any>()
      s = Automerge.change(s, doc => (doc.config = { background: "blue" }))
      s = Automerge.change(s, doc => (doc.birds = ["mallard"]))
      s = Automerge.change(s, doc => doc.birds.unshift("oystercatcher"))
      assert.deepStrictEqual(
        Automerge.getHistory(s).map(state => state.snapshot),
        [
          { config: { background: "blue" } },
          { config: { background: "blue" }, birds: ["mallard"] },
          {
            config: { background: "blue" },
            birds: ["oystercatcher", "mallard"],
          },
        ]
      )
    })

    it("should make change messages accessible", () => {
      let s = Automerge.init<any>()
      s = Automerge.change(s, "Empty Bookshelf", doc => (doc.books = []))
      s = Automerge.change(s, "Add Orwell", doc =>
        doc.books.push("Nineteen Eighty-Four")
      )
      s = Automerge.change(s, "Add Huxley", doc =>
        doc.books.push("Brave New World")
      )
      assert.deepStrictEqual(s.books, [
        "Nineteen Eighty-Four",
        "Brave New World",
      ])
      assert.deepStrictEqual(
        Automerge.getHistory(s).map(state => state.change.message),
        ["Empty Bookshelf", "Add Orwell", "Add Huxley"]
      )
    })
  })

  describe("changes API", () => {
    it("should return an empty list on an empty document", () => {
      let changes = Automerge.getAllChanges(Automerge.init())
      assert.deepStrictEqual(changes, [])
    })

    it("should return an empty list when nothing changed", () => {
      let s1 = Automerge.change(
        Automerge.init<any>(),
        doc => (doc.birds = ["Chaffinch"])
      )
      assert.deepStrictEqual(Automerge.getChanges(s1, s1), [])
    })

    it("should do nothing when applying an empty list of changes", () => {
      let s1 = Automerge.change(
        Automerge.init<any>(),
        doc => (doc.birds = ["Chaffinch"])
      )
      assert.deepStrictEqual(Automerge.applyChanges(s1, [])[0], s1)
    })

    it("should return all changes when compared to an empty document", () => {
      let s1 = Automerge.change(
        Automerge.init<any>(),
        "Add Chaffinch",
        doc => (doc.birds = ["Chaffinch"])
      )
      let s2 = Automerge.change(s1, "Add Bullfinch", doc =>
        doc.birds.push("Bullfinch")
      )
      let changes = Automerge.getChanges(Automerge.init(), s2)
      assert.strictEqual(changes.length, 2)
    })

    it("should allow a document copy to be reconstructed from scratch", () => {
      let s1 = Automerge.change(
        Automerge.init<any>(),
        "Add Chaffinch",
        doc => (doc.birds = ["Chaffinch"])
      )
      let s2 = Automerge.change(s1, "Add Bullfinch", doc =>
        doc.birds.push("Bullfinch")
      )
      let changes = Automerge.getAllChanges(s2)
      let [s3] = Automerge.applyChanges(Automerge.init<any>(), changes)
      assert.deepStrictEqual(s3.birds, ["Chaffinch", "Bullfinch"])
    })

    it("should return changes since the last given version", () => {
      let s1 = Automerge.change(
        Automerge.init<any>(),
        "Add Chaffinch",
        doc => (doc.birds = ["Chaffinch"])
      )
      let changes1 = Automerge.getAllChanges(s1)
      let s2 = Automerge.change(s1, "Add Bullfinch", doc =>
        doc.birds.push("Bullfinch")
      )
      let changes2 = Automerge.getChanges(s1, s2)
      assert.strictEqual(changes1.length, 1) // Add Chaffinch
      assert.strictEqual(changes2.length, 1) // Add Bullfinch
    })

    it("should incrementally apply changes since the last given version", () => {
      let s1 = Automerge.change(
        Automerge.init<any>(),
        "Add Chaffinch",
        doc => (doc.birds = ["Chaffinch"])
      )
      let changes1 = Automerge.getAllChanges(s1)
      let s2 = Automerge.change(s1, "Add Bullfinch", doc =>
        doc.birds.push("Bullfinch")
      )
      let changes2 = Automerge.getChanges(s1, s2)
      let [s3] = Automerge.applyChanges(Automerge.init<any>(), changes1)
      let [s4] = Automerge.applyChanges(s3, changes2)
      assert.deepStrictEqual(s3.birds, ["Chaffinch"])
      assert.deepStrictEqual(s4.birds, ["Chaffinch", "Bullfinch"])
    })

    it("should handle updates to a list element", () => {
      let s1 = Automerge.change(
        Automerge.init<any>(),
        doc => (doc.birds = ["Chaffinch", "Bullfinch"])
      )
      let s2 = Automerge.change(s1, doc => (doc.birds[0] = "Goldfinch"))
      let [s3] = Automerge.applyChanges(
        Automerge.init<any>(),
        Automerge.getAllChanges(s2)
      )
      assert.deepStrictEqual(s3.birds, ["Goldfinch", "Bullfinch"])
      assert.strictEqual(Automerge.getConflicts(s3.birds, 0), undefined)
    })

    // TEXT
    it("should handle updates to a text object", () => {
      let s1 = Automerge.change(Automerge.init<any>(), doc => (doc.text = "ab"))
      let s2 = Automerge.change(s1, doc =>
        Automerge.splice(doc, "text", 0, 1, "A")
      )
      let [s3] = Automerge.applyChanges(
        Automerge.init<any>(),
        Automerge.getAllChanges(s2)
      )
      assert.deepStrictEqual([...s3.text], ["A", "b"])
    })

    /*
    it.skip('should report missing dependencies', () => {
      let s1 = Automerge.change(Automerge.init(), doc => doc.birds = ['Chaffinch'])
      let s2 = Automerge.merge(Automerge.init(), s1)
      s2 = Automerge.change(s2, doc => doc.birds.push('Bullfinch'))
      let changes = Automerge.getAllChanges(s2)
      let [s3, patch] = Automerge.applyChanges(Automerge.init(), [changes[1]])
      assert.deepStrictEqual(s3, {})
      assert.deepStrictEqual(Automerge.Backend.getMissingDeps(Automerge.Frontend.getBackendState(s3)),
                             decodeChange(changes[1]).deps)
      assert.strictEqual(patch.pendingChanges, 1)
      ;[s3, patch] = Automerge.applyChanges(s3, [changes[0]])
      assert.deepStrictEqual(s3.birds, ['Chaffinch', 'Bullfinch'])
      assert.deepStrictEqual(Automerge.Backend.getMissingDeps(Automerge.Frontend.getBackendState(s3)), [])
      assert.strictEqual(patch.pendingChanges, 0)
    })
    */

    it("should report missing dependencies with out-of-order applyChanges", () => {
      let s0 = Automerge.init<any>()
      let s1 = Automerge.change(s0, doc => (doc.test = ["a"]))
      let changes01 = Automerge.getAllChanges(s1)
      let s2 = Automerge.change(s1, doc => (doc.test = ["b"]))
      let changes12 = Automerge.getChanges(s1, s2)
      let s3 = Automerge.change(s2, doc => (doc.test = ["c"]))
      let changes23 = Automerge.getChanges(s2, s3)
      let s4 = Automerge.init()
      let [s5] = Automerge.applyChanges(s4, changes23)
      let [s6] = Automerge.applyChanges(s5, changes12)
      assert.deepStrictEqual(Automerge.getMissingDeps(s6, []), [
        decodeChange(changes01[0]).hash,
      ])
    })

    it("should call patchCallback if supplied when applying changes", () => {
      const s1 = Automerge.change(
        Automerge.init<any>(),
        doc => (doc.birds = ["Goldfinch"])
      )
      const callbacks: Array<any> = []
      const before = Automerge.init()
      const [after] = Automerge.applyChanges(
        before,
        Automerge.getAllChanges(s1),
        {
          patchCallback(patch, before, after) {
            callbacks.push({ patch, before, after })
          },
        }
      )
      assert.strictEqual(callbacks.length, 1)
      assert.deepStrictEqual(callbacks[0].patch[0], {
        action: "put",
        path: ["birds"],
        value: [],
      })
      assert.deepStrictEqual(callbacks[0].patch[1], {
        action: "insert",
        path: ["birds", 0],
        values: [""],
      })
      assert.deepStrictEqual(callbacks[0].patch[2], {
        action: "splice",
        path: ["birds", 0, 0],
        value: "Goldfinch",
      })
      assert.strictEqual(callbacks[0].before, before)
      assert.strictEqual(callbacks[0].after, after)
    })

    it("should merge multiple applied changes into one patch", () => {
      const s1 = Automerge.change(
        Automerge.init<any>(),
        doc => (doc.birds = ["Goldfinch"])
      )
      const s2 = Automerge.change(s1, doc => doc.birds.push("Chaffinch"))
      const patches: Array<any> = []
      Automerge.applyChanges(Automerge.init(), Automerge.getAllChanges(s2), {
        patchCallback: p => patches.push(...p),
      })
      assert.deepStrictEqual(patches, [
        { action: "put", path: ["birds"], value: [] },
        { action: "insert", path: ["birds", 0], values: ["", ""] },
        { action: "splice", path: ["birds", 0, 0], value: "Goldfinch" },
        { action: "splice", path: ["birds", 1, 0], value: "Chaffinch" },
      ])
    })

    it("should call a patchCallback registered on doc initialisation", () => {
      const s1 = Automerge.change(
        Automerge.init<any>(),
        doc => (doc.bird = "Goldfinch")
      )
      const patches: Array<any> = []
      const before = Automerge.init({
        patchCallback: p => patches.push(...p),
      })
      Automerge.applyChanges(before, Automerge.getAllChanges(s1))
      assert.deepStrictEqual(patches, [
        { action: "put", path: ["bird"], value: "" },
        { action: "splice", path: ["bird", 0], value: "Goldfinch" },
      ])
    })
  })
})