Fix deep merge when previously empty

Swizz · Aug 26, 2019 · 4e909fa · 4e909fa
1 parent ccd9ccd
commit 4e909fa
Show file tree

Hide file tree

Showing 2 changed files with 124 additions and 2 deletions.
diff --git a/src/index.js b/src/index.js
@@ -8,7 +8,7 @@ export function diff(from, to, deep) {
   for (var key in to) {
     if (key in done || from[key] === to[key]) continue
 
-    if (deep && (typeof from[key] === "object" || typeof to[key] === "object")) {
+    if (deep && (typeof from[key] === "object" && typeof to[key] === "object")) {
       var deep_patch = diff(from[key], to[key], deep)
 
       if (Object.keys(deep_patch.do).length) {
@@ -59,4 +59,4 @@ export function patch(from, diff, deep, array, clean) {
     }
   }
   return array && "length" in to ? Array.from(to) : to
-}
+}
diff --git a/tests/diff.test.js b/tests/diff.test.js
@@ -345,3 +345,125 @@ describe("array", () => {
     expect(Array.from({ ...to, ...patch.undo })).toEqual(from)
   })
 })
+
+describe("empty", () => {
+  test("empty from", () => {
+    const from = {}
+
+    const to = { a: 1 }
+
+    const patch = diff(from, to)
+
+    expect(patch.do).toEqual(to)
+
+    expect(patch.undo).toEqual({
+      a: undefined
+    })
+
+    expect({ ...from, ...patch.do }).toEqual(to)
+
+    expect({ ...to, ...patch.undo }).toEqual(from)
+  })
+
+  test("empty to", () => {
+    const from = { a: 1 }
+
+    const to = {}
+
+    const patch = diff(from, to)
+
+    expect(patch.do).toEqual({
+      a: undefined
+    })
+
+    expect(patch.undo).toEqual(from)
+
+    expect({ ...from, ...patch.do }).toEqual(to)
+
+    expect({ ...to, ...patch.undo }).toEqual(from)
+  })
+})
+
+describe("empty array", () => {
+  test("empty from", () => {
+    const from = []
+
+    const to = [1]
+
+    const patch = diff(from, to)
+
+    expect(patch.do).toEqual({
+      0: 1,
+      length: 1
+    })
+
+    expect(patch.undo).toEqual({
+      0: undefined,
+      length: 0
+    })
+
+    expect(Array.from({ ...from, ...patch.do })).toEqual(to)
+
+    expect(Array.from({ ...to, ...patch.undo })).toEqual(from)
+  })
+
+  test("empty to", () => {
+    const from = [1]
+
+    const to = []
+
+    const patch = diff(from, to)
+
+    expect(patch.do).toEqual({
+      0: undefined,
+      length: 0
+    })
+
+    expect(patch.undo).toEqual({
+      0: 1,
+      length: 1
+    })
+
+    expect(Array.from({ ...from, ...patch.do })).toEqual(to)
+
+    expect(Array.from({ ...to, ...patch.undo })).toEqual(from)
+  })
+})
+
+describe("deep empty", () => {
+  test("deep empty object", () => {
+    const from = {}
+
+    const to = { a: { b: 1 } }
+
+    const patch = diff(from, to, true)
+
+    expect(patch.do).toEqual(to)
+
+    expect(patch.undo).toEqual({
+      a: undefined
+    })
+
+    expect({ ...from, ...patch.do }).toEqual(to)
+
+    expect({ ...to, ...patch.undo }).toEqual(from)
+  })
+
+  test("deep empty array", () => {
+    const from = {}
+
+    const to = { a: [1] }
+
+    const patch = diff(from, to, true)
+
+    expect(patch.do).toEqual(to)
+
+    expect(patch.undo).toEqual({
+      a: undefined
+    })
+
+    expect({ ...from, ...patch.do }).toEqual(to)
+
+    expect({ ...to, ...patch.undo }).toEqual(from)
+  })
+})