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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 myers_test
import (
"flag"
"fmt"
"io/ioutil"
"os"
"os/exec"
"reflect"
"strings"
"testing"
"golang.org/x/tools/internal/lsp/diff/myers"
)
const (
fileA = "a/a.go"
fileB = "b/b.go"
unifiedPrefix = "--- " + fileA + "\n+++ " + fileB + "\n"
)
var verifyDiff = flag.Bool("verify-diff", false, "Check that the unified diff output matches `diff -u`")
func TestDiff(t *testing.T) {
for _, test := range []struct {
a, b string
lines []*myers.Op
operations []*myers.Op
unified string
nodiff bool
}{
{
a: "A\nB\nC\n",
b: "A\nB\nC\n",
operations: []*myers.Op{},
unified: `
`[1:]}, {
a: "A\n",
b: "B\n",
operations: []*myers.Op{
&myers.Op{Kind: myers.Delete, I1: 0, I2: 1, J1: 0},
&myers.Op{Kind: myers.Insert, Content: []string{"B\n"}, I1: 1, I2: 1, J1: 0},
},
unified: `
@@ -1 +1 @@
-A
+B
`[1:]}, {
a: "A",
b: "B",
operations: []*myers.Op{
&myers.Op{Kind: myers.Delete, I1: 0, I2: 1, J1: 0},
&myers.Op{Kind: myers.Insert, Content: []string{"B"}, I1: 1, I2: 1, J1: 0},
},
unified: `
@@ -1 +1 @@
-A
\ No newline at end of file
+B
\ No newline at end of file
`[1:]}, {
a: "A\nB\nC\nA\nB\nB\nA\n",
b: "C\nB\nA\nB\nA\nC\n",
operations: []*myers.Op{
&myers.Op{Kind: myers.Delete, I1: 0, I2: 1, J1: 0},
&myers.Op{Kind: myers.Delete, I1: 1, I2: 2, J1: 0},
&myers.Op{Kind: myers.Insert, Content: []string{"B\n"}, I1: 3, I2: 3, J1: 1},
&myers.Op{Kind: myers.Delete, I1: 5, I2: 6, J1: 4},
&myers.Op{Kind: myers.Insert, Content: []string{"C\n"}, I1: 7, I2: 7, J1: 5},
},
unified: `
@@ -1,7 +1,6 @@
-A
-B
C
+B
A
B
-B
A
+C
`[1:],
nodiff: true, // diff algorithm produces different delete/insert pattern
},
{
a: "A\nB\n",
b: "A\nC\n\n",
operations: []*myers.Op{
&myers.Op{Kind: myers.Delete, I1: 1, I2: 2, J1: 1},
&myers.Op{Kind: myers.Insert, Content: []string{"C\n"}, I1: 2, I2: 2, J1: 1},
&myers.Op{Kind: myers.Insert, Content: []string{"\n"}, I1: 2, I2: 2, J1: 2},
},
unified: `
@@ -1,2 +1,3 @@
A
-B
+C
+
`[1:],
},
{
a: "A\nB\nC\nD\nE\nF\nG\n",
b: "A\nH\nI\nJ\nE\nF\nK\n",
unified: `
@@ -1,7 +1,7 @@
A
-B
-C
-D
+H
+I
+J
E
F
-G
+K
`[1:]},
} {
a := myers.SplitLines(test.a)
b := myers.SplitLines(test.b)
ops := myers.Operations(a, b)
if test.operations != nil {
if len(ops) != len(test.operations) {
t.Fatalf("expected %v operations, got %v", len(test.operations), len(ops))
}
for i, got := range ops {
want := test.operations[i]
if !reflect.DeepEqual(want, got) {
t.Errorf("expected %v, got %v", want, got)
}
}
}
applied := myers.ApplyEdits(a, ops)
for i, want := range applied {
got := b[i]
if got != want {
t.Errorf("expected %v got %v", want, got)
}
}
if test.unified != "" {
diff := myers.ToUnified(fileA, fileB, a, ops)
got := fmt.Sprint(diff)
if !strings.HasPrefix(got, unifiedPrefix) {
t.Errorf("expected prefix:\n%s\ngot:\n%s", unifiedPrefix, got)
continue
}
got = got[len(unifiedPrefix):]
if test.unified != got {
t.Errorf("expected:\n%q\ngot:\n%q", test.unified, got)
}
}
if *verifyDiff && test.unified != "" && !test.nodiff {
diff, err := getDiffOutput(test.a, test.b)
if err != nil {
t.Fatal(err)
}
if diff != test.unified {
t.Errorf("unified:\n%q\ndiff -u:\n%q", test.unified, diff)
}
}
}
}
func getDiffOutput(a, b string) (string, error) {
fileA, err := ioutil.TempFile("", "myers.in")
if err != nil {
return "", err
}
defer os.Remove(fileA.Name())
if _, err := fileA.Write([]byte(a)); err != nil {
return "", err
}
if err := fileA.Close(); err != nil {
return "", err
}
fileB, err := ioutil.TempFile("", "myers.in")
if err != nil {
return "", err
}
defer os.Remove(fileB.Name())
if _, err := fileB.Write([]byte(b)); err != nil {
return "", err
}
if err := fileB.Close(); err != nil {
return "", err
}
cmd := exec.Command("diff", "-u", fileA.Name(), fileB.Name())
out, err := cmd.CombinedOutput()
if err != nil {
if _, ok := err.(*exec.ExitError); !ok {
return "", fmt.Errorf("failed to run diff -u %v %v: %v\n%v", fileA.Name(), fileB.Name(), err, string(out))
}
}
diff := string(out)
bits := strings.SplitN(diff, "\n", 3)
if len(bits) != 3 {
return "", fmt.Errorf("diff output did not have file prefix:\n%s", diff)
}
return bits[2], nil
}