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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_test
import (
"fmt"
"os"
"os/exec"
"strings"
"testing"
"golang.org/x/tools/internal/diff/difftest"
"golang.org/x/tools/internal/testenv"
)
func TestVerifyUnified(t *testing.T) {
testenv.NeedsTool(t, "diff")
for _, test := range difftest.TestCases {
t.Run(test.Name, func(t *testing.T) {
if test.NoDiff {
t.Skip("diff tool produces expected different results")
}
diff, err := getDiffOutput(test.In, test.Out)
if err != nil {
t.Fatal(err)
}
if len(diff) > 0 {
diff = difftest.UnifiedPrefix + diff
}
if diff != test.Unified {
t.Errorf("unified:\n%s\ndiff -u:\n%s", test.Unified, diff)
}
})
}
}
func getDiffOutput(a, b string) (string, error) {
fileA, err := os.CreateTemp("", "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 := os.CreateTemp("", "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())
cmd.Env = append(cmd.Env, "LANG=en_US.UTF-8")
out, err := cmd.Output()
if err != nil {
exit, ok := err.(*exec.ExitError)
if !ok {
return "", fmt.Errorf("can't exec %s: %v", cmd, err)
}
if len(out) == 0 {
// Nonzero exit with no output: terminated by signal?
return "", fmt.Errorf("%s failed: %v; stderr:\n%s", cmd, err, exit.Stderr)
}
// nonzero exit + output => files differ
}
diff := string(out)
if len(diff) <= 0 {
return diff, nil
}
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
}
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