cmd/dist: add test that deps.go is up to date

Test is not run in short mode, except on builders.

Change-Id: I4456830770188951e05ac13669e834a25bf569ae
Reviewed-on: https://go-review.googlesource.com/55973
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Run-TryBot: Joe Tsai <joetsai@google.com>
Reviewed-by: Joe Tsai <joetsai@google.com>
Reviewed-by: Marvin Stenger <marvin.stenger94@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/dist/deps_test.go

+// Copyright 2017 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 main_test
+
+import (
+	"bytes"
+	"internal/testenv"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"strings"
+	"testing"
+)
+
+func TestDeps(t *testing.T) {
+	if testing.Short() && testenv.Builder() == "" {
+		t.Skip("skipping in short mode")
+	}
+
+	current, err := ioutil.ReadFile("deps.go")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	bash, err := exec.LookPath("bash")
+	if err != nil {
+		t.Skipf("skipping because bash not found: %v", err)
+	}
+
+	outf, err := ioutil.TempFile("", "dist-deps-test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	outf.Close()
+	outname := outf.Name()
+	defer os.Remove(outname)
+
+	out, err := exec.Command(bash, "mkdeps.bash", outname).CombinedOutput()
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("%s", out)
+
+	updated, err := ioutil.ReadFile(outname)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !bytes.Equal(current, updated) {
+		// Very simple minded diff.
+		t.Log("-current +generated")
+		clines := strings.Split(string(current), "\n")
+		ulines := strings.Split(string(updated), "\n")
+		for len(clines) > 0 {
+			cl := clines[0]
+			switch {
+			case len(ulines) == 0:
+				t.Logf("-%s", cl)
+				clines = clines[1:]
+			case cl == ulines[0]:
+				clines = clines[1:]
+				ulines = ulines[1:]
+			case pkg(cl) == pkg(ulines[0]):
+				t.Logf("-%s", cl)
+				t.Logf("+%s", ulines[0])
+				clines = clines[1:]
+				ulines = ulines[1:]
+			case pkg(cl) < pkg(ulines[0]):
+				t.Logf("-%s", cl)
+				clines = clines[1:]
+			default:
+				cp := pkg(cl)
+				for len(ulines) > 0 && pkg(ulines[0]) < cp {
+					t.Logf("+%s", ulines[0])
+					ulines = ulines[1:]
+				}
+			}
+		}
+
+		t.Error("cmd/dist/deps.go is out of date; run cmd/dist/mkdeps.bash")
+	}
+}
+
+// pkg returns the package of a line in deps.go.
+func pkg(line string) string {
+	i := strings.Index(line, `"`)
+	if i < 0 {
+		return ""
+	}
+	line = line[i+1:]
+	i = strings.Index(line, `"`)
+	if i < 0 {
+		return ""
+	}
+	return line[:i]
+}

src/cmd/dist/mkdeps.bash

@@ -5,6 +5,11 @@
 
 set -e
 
+output="$1"
+if test -z "$output"; then
+    output=deps.go
+fi
+
 # We need to test enough GOOS/GOARCH combinations to pick up all the
 # package dependencies.
 gooslist="windows linux darwin solaris"
@@ -42,6 +47,6 @@ deps_of $all >tmp.all.deps
 		echo '},'
 	done
 	echo '}'
-) |gofmt >deps.go
+) |gofmt >$output
 
 rm -f tmp.all.deps