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go/internal/lsp/diff/difftest/difftest_test.go
Richard Miller 19e4049dcd internal/testenv: check that external 'diff' tool is the GNU version
TestVerifyUnified in internal/lsp/diff/difftest requires specific
behaviour of the 'diff' command which is known to be satisfied by
GNU diff. The plan9 'diff' command has no '-u' option, and the
illumos 'diff -u' produces output in a different format. Checking
specifically for the GNU version in the HasTool function ensures
the expected behaviour, and otherwise causes the test to be skipped.

Updates golang/go#38772

Change-Id: I5493fa8cfc48a112dc0b7356618c62d3ccb0366f
Reviewed-on: https://go-review.googlesource.com/c/tools/+/232479
Reviewed-by: Ian Cottrell <iancottrell@google.com>
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2020-05-08 20:46:49 +00:00

84 lines
2.0 KiB
Go

// 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/lsp/diff"
package difftest_test
import (
"fmt"
"io/ioutil"
"os"
"os/exec"
"strings"
"testing"
"golang.org/x/tools/internal/lsp/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) {
t.Helper()
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%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)
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
}