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// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package difftest supplies a set of tests that will operate on any
// implementation of a diff algorithm as exposed by
// "golang.org/x/tools/internal/diff"
package difftest
// There are two kinds of tests, semantic tests, and 'golden data' tests.
// The semantic tests check that the computed diffs transform the input to
// the output, and that 'patch' accepts the computed unified diffs.
// The other tests just check that Edits and LineEdits haven't changed
// unexpectedly. These fields may need to be changed when the diff algorithm
// changes.
import (
"testing"
"golang.org/x/tools/internal/diff"
)
const (
FileA = "from"
FileB = "to"
UnifiedPrefix = "--- " + FileA + "\n+++ " + FileB + "\n"
)
var TestCases = []struct {
Name, In, Out, Unified string
Edits, LineEdits []diff.Edit
NoDiff bool
}{{
Name: "empty",
In: "",
Out: "",
}, {
Name: "no_diff",
In: "gargantuan\n",
Out: "gargantuan\n",
}, {
Name: "replace_all",
In: "fruit\n",
Out: "cheese\n",
Unified: UnifiedPrefix + `
@@ -1 +1 @@
-fruit
+cheese
`[1:],
Edits: []diff.Edit{{Start: 0, End: 5, New: "cheese"}},
LineEdits: []diff.Edit{{Start: 0, End: 6, New: "cheese\n"}},
}, {
Name: "insert_rune",
In: "gord\n",
Out: "gourd\n",
Unified: UnifiedPrefix + `
@@ -1 +1 @@
-gord
+gourd
`[1:],
Edits: []diff.Edit{{Start: 2, End: 2, New: "u"}},
LineEdits: []diff.Edit{{Start: 0, End: 5, New: "gourd\n"}},
}, {
Name: "delete_rune",
In: "groat\n",
Out: "goat\n",
Unified: UnifiedPrefix + `
@@ -1 +1 @@
-groat
+goat
`[1:],
Edits: []diff.Edit{{Start: 1, End: 2, New: ""}},
LineEdits: []diff.Edit{{Start: 0, End: 6, New: "goat\n"}},
}, {
Name: "replace_rune",
In: "loud\n",
Out: "lord\n",
Unified: UnifiedPrefix + `
@@ -1 +1 @@
-loud
+lord
`[1:],
Edits: []diff.Edit{{Start: 2, End: 3, New: "r"}},
LineEdits: []diff.Edit{{Start: 0, End: 5, New: "lord\n"}},
}, {
Name: "replace_partials",
In: "blanket\n",
Out: "bunker\n",
Unified: UnifiedPrefix + `
@@ -1 +1 @@
-blanket
+bunker
`[1:],
Edits: []diff.Edit{
{Start: 1, End: 3, New: "u"},
{Start: 6, End: 7, New: "r"},
},
LineEdits: []diff.Edit{{Start: 0, End: 8, New: "bunker\n"}},
}, {
Name: "insert_line",
In: "1: one\n3: three\n",
Out: "1: one\n2: two\n3: three\n",
Unified: UnifiedPrefix + `
@@ -1,2 +1,3 @@
1: one
+2: two
3: three
`[1:],
Edits: []diff.Edit{{Start: 7, End: 7, New: "2: two\n"}},
}, {
Name: "replace_no_newline",
In: "A",
Out: "B",
Unified: UnifiedPrefix + `
@@ -1 +1 @@
-A
\ No newline at end of file
+B
\ No newline at end of file
`[1:],
Edits: []diff.Edit{{Start: 0, End: 1, New: "B"}},
}, {
Name: "append_empty",
In: "", // GNU diff -u special case: -0,0
Out: "AB\nC",
Unified: UnifiedPrefix + `
@@ -0,0 +1,2 @@
+AB
+C
\ No newline at end of file
`[1:],
Edits: []diff.Edit{{Start: 0, End: 0, New: "AB\nC"}},
LineEdits: []diff.Edit{{Start: 0, End: 0, New: "AB\nC"}},
},
// TODO(adonovan): fix this test: GNU diff -u prints "+1,2", Unifies prints "+1,3".
// {
// Name: "add_start",
// In: "A",
// Out: "B\nCA",
// Unified: UnifiedPrefix + `
// @@ -1 +1,2 @@
// -A
// \ No newline at end of file
// +B
// +CA
// \ No newline at end of file
// `[1:],
// Edits: []diff.TextEdit{{Span: newSpan(0, 0), NewText: "B\nC"}},
// LineEdits: []diff.TextEdit{{Span: newSpan(0, 0), NewText: "B\nC"}},
// },
{
Name: "add_end",
In: "A",
Out: "AB",
Unified: UnifiedPrefix + `
@@ -1 +1 @@
-A
\ No newline at end of file
+AB
\ No newline at end of file
`[1:],
Edits: []diff.Edit{{Start: 1, End: 1, New: "B"}},
LineEdits: []diff.Edit{{Start: 0, End: 1, New: "AB"}},
}, {
Name: "add_empty",
In: "",
Out: "AB\nC",
Unified: UnifiedPrefix + `
@@ -0,0 +1,2 @@
+AB
+C
\ No newline at end of file
`[1:],
Edits: []diff.Edit{{Start: 0, End: 0, New: "AB\nC"}},
LineEdits: []diff.Edit{{Start: 0, End: 0, New: "AB\nC"}},
}, {
Name: "add_newline",
In: "A",
Out: "A\n",
Unified: UnifiedPrefix + `
@@ -1 +1 @@
-A
\ No newline at end of file
+A
`[1:],
Edits: []diff.Edit{{Start: 1, End: 1, New: "\n"}},
LineEdits: []diff.Edit{{Start: 0, End: 1, New: "A\n"}},
}, {
Name: "delete_front",
In: "A\nB\nC\nA\nB\nB\nA\n",
Out: "C\nB\nA\nB\nA\nC\n",
Unified: UnifiedPrefix + `
@@ -1,7 +1,6 @@
-A
-B
C
+B
A
B
-B
A
+C
`[1:],
NoDiff: true, // unified diff is different but valid
Edits: []diff.Edit{
{Start: 0, End: 4, New: ""},
{Start: 6, End: 6, New: "B\n"},
{Start: 10, End: 12, New: ""},
{Start: 14, End: 14, New: "C\n"},
},
LineEdits: []diff.Edit{
{Start: 0, End: 6, New: "C\n"},
{Start: 6, End: 8, New: "B\nA\n"},
{Start: 10, End: 14, New: "A\n"},
{Start: 14, End: 14, New: "C\n"},
},
}, {
Name: "replace_last_line",
In: "A\nB\n",
Out: "A\nC\n\n",
Unified: UnifiedPrefix + `
@@ -1,2 +1,3 @@
A
-B
+C
+
`[1:],
Edits: []diff.Edit{{Start: 2, End: 3, New: "C\n"}},
LineEdits: []diff.Edit{{Start: 2, End: 4, New: "C\n\n"}},
},
{
Name: "multiple_replace",
In: "A\nB\nC\nD\nE\nF\nG\n",
Out: "A\nH\nI\nJ\nE\nF\nK\n",
Unified: UnifiedPrefix + `
@@ -1,7 +1,7 @@
A
-B
-C
-D
+H
+I
+J
E
F
-G
+K
`[1:],
Edits: []diff.Edit{
{Start: 2, End: 8, New: "H\nI\nJ\n"},
{Start: 12, End: 14, New: "K\n"},
},
NoDiff: true, // diff algorithm produces different delete/insert pattern
},
{
Name: "extra_newline",
In: "\nA\n",
Out: "A\n",
Edits: []diff.Edit{{Start: 0, End: 1, New: ""}},
Unified: UnifiedPrefix + `@@ -1,2 +1 @@
-
A
`,
},
}
func DiffTest(t *testing.T, compute func(before, after string) []diff.Edit) {
for _, test := range TestCases {
t.Run(test.Name, func(t *testing.T) {
edits := compute(test.In, test.Out)
got, err := diff.Apply(test.In, edits)
if err != nil {
t.Fatalf("Apply failed: %v", err)
}
unified, err := diff.ToUnified(FileA, FileB, test.In, edits)
if err != nil {
t.Fatalf("ToUnified: %v", err)
}
if got != test.Out {
t.Errorf("Apply: got patched:\n%v\nfrom diff:\n%v\nexpected:\n%v",
got, unified, test.Out)
}
if !test.NoDiff && unified != test.Unified {
t.Errorf("Unified: got diff:\n%q\nexpected:\n%q diffs:%v",
unified, test.Unified, edits)
}
})
}
}