refactor/rename: make tests pass on windows (fixes build)

- use import path not file path in go/buildutil.FakeContext OpenFile;
- use regexp to compare error messages in TestErrors, because
  they contain windows file paths;
- use OS file path (not unix path), when checking move results
  in TestMoves.

Change-Id: Ib62d344acb551fb612d8a0773ae1ab5f18341294
Reviewed-on: https://go-review.googlesource.com/3171
Reviewed-by: Alan Donovan <adonovan@google.com>

go/buildutil/fakecontext.go

@@ -67,8 +67,8 @@ func FakeContext(pkgs map[string]map[string]string) *build.Context {
 	}
 	ctxt.OpenFile = func(filename string) (io.ReadCloser, error) {
 		filename = clean(filename)
-		dir, base := filepath.Split(filename)
-		content, ok := pkgs[filepath.Clean(dir)][base]
+		dir, base := path.Split(filename)
+		content, ok := pkgs[path.Clean(dir)][base]
 		if !ok {
 			return nil, fmt.Errorf("file not found: %s", filename)
 		}

refactor/rename/mvpkg_test.go

@@ -13,6 +13,7 @@ import (
 	"go/token"
 	"io/ioutil"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"sync"
 	"testing"
@@ -39,7 +40,7 @@ var _ foo.T
 `},
 			}),
 			from: "foo", to: "bar",
-			want: "invalid move destination: bar conflicts with directory /go/src/bar",
+			want: `invalid move destination: bar conflicts with directory .go.src.bar`,
 		},
 		// Subpackage already exists.
 		{
@@ -104,7 +105,12 @@ var _ foo.T
 			t.Errorf("%s: nil error. Expected error: %s", prefix, test.want)
 			continue
 		}
-		if test.want != err.Error() {
+		matched, err2 := regexp.MatchString(test.want, err.Error())
+		if err2 != nil {
+			t.Errorf("regexp.MatchString failed %s", err2)
+			continue
+		}
+		if !matched {
 			t.Errorf("%s: conflict does not match expectation:\n"+
 				"Error: %q\n"+
 				"Pattern: %q",
@@ -235,8 +241,9 @@ type T int
 		}
 
 		for file, wantContent := range test.want {
-			gotContent, ok := got[file]
-			delete(got, file)
+			k := filepath.FromSlash(file)
+			gotContent, ok := got[k]
+			delete(got, k)
 			if !ok {
 				// TODO(matloob): some testcases might have files that won't be
 				// rewritten