include testing for absence in checked diff

Author: cppforlife

patch/diff.go

@@ -61,8 +61,13 @@ func (d Diff) calculate(left, right interface{}, tokens []Token) []Op {
 						)
 					}
 				} else { // add new
+					testOpTokens := append([]Token{}, newTokens...)
+					testOpTokens = append(testOpTokens, KeyToken{Key: fmt.Sprintf("%s", k)})
 					newTokens = append(newTokens, KeyToken{Key: fmt.Sprintf("%s", k), Optional: true})
-					ops = append(ops, ReplaceOp{Path: NewPointer(newTokens), Value: typedRight[k]})
+					ops = append(ops,
+						TestOp{Path: NewPointer(testOpTokens), Absent: true},
+						ReplaceOp{Path: NewPointer(newTokens), Value: typedRight[k]},
+					)
 				}
 			}
 			return ops
@@ -87,8 +92,13 @@ func (d Diff) calculate(left, right interface{}, tokens []Token) []Op {
 					)
 					// keep actualIndex the same
 				case i >= len(typedLeft): // add new
+					testOpTokens := append([]Token{}, newTokens...)
+					testOpTokens = append(testOpTokens, IndexToken{Index: i}) // use actual index
 					newTokens = append(newTokens, AfterLastIndexToken{})
-					ops = append(ops, ReplaceOp{Path: NewPointer(newTokens), Value: typedRight[i]})
+					ops = append(ops,
+						TestOp{Path: NewPointer(testOpTokens), Absent: true},
+						ReplaceOp{Path: NewPointer(newTokens), Value: typedRight[i]},
+					)
 					actualIndex++
 				default:
 					newTokens = append(newTokens, IndexToken{Index: actualIndex})

patch/diff_test.go

@@ -87,6 +87,7 @@ var _ = Describe("Diff.Calculate", func() {
 				ReplaceOp{Path: MustNewPointerFromString("/a"), Value: 124},
 				TestOp{Path: MustNewPointerFromString("/b"), Value: 456},
 				RemoveOp{Path: MustNewPointerFromString("/b")},
+				TestOp{Path: MustNewPointerFromString("/c"), Absent: true},
 				ReplaceOp{Path: MustNewPointerFromString("/c?"), Value: 456},
 			},
 		)
@@ -130,6 +131,7 @@ var _ = Describe("Diff.Calculate", func() {
 				ReplaceOp{Path: MustNewPointerFromString("/a"), Value: 124},
 				TestOp{Path: MustNewPointerFromString("/b/b"), Value: 4056},
 				RemoveOp{Path: MustNewPointerFromString("/b/b")},
+				TestOp{Path: MustNewPointerFromString("/b/c"), Absent: true},
 				ReplaceOp{Path: MustNewPointerFromString("/b/c?"), Value: 4056},
 			},
 		)
@@ -169,7 +171,9 @@ var _ = Describe("Diff.Calculate", func() {
 			[]Op{
 				TestOp{Path: MustNewPointerFromString("/0"), Value: "a"},
 				ReplaceOp{Path: MustNewPointerFromString("/0"), Value: "b"},
+				TestOp{Path: MustNewPointerFromString("/1"), Absent: true},
 				ReplaceOp{Path: MustNewPointerFromString("/-"), Value: 123},
+				TestOp{Path: MustNewPointerFromString("/2"), Absent: true},
 				ReplaceOp{Path: MustNewPointerFromString("/-"), Value: 456},
 			},
 		)
@@ -204,6 +208,7 @@ var _ = Describe("Diff.Calculate", func() {
 			[]Op{
 				TestOp{Path: MustNewPointerFromString("/1"), Value: 456},
 				ReplaceOp{Path: MustNewPointerFromString("/1"), Value: "a"},
+				TestOp{Path: MustNewPointerFromString("/2"), Absent: true},
 				ReplaceOp{Path: MustNewPointerFromString("/-"), Value: 456},
 			},
 		)