go/loader: fix tests to work at go1.5 and tip

Change-Id: Icc80f112a7ec4b64519220c57b6ccb2612166656
Reviewed-on: https://go-review.googlesource.com/18197
Reviewed-by: Alan Donovan <adonovan@google.com>

go/buildutil/util_test.go

@@ -23,15 +23,21 @@ func TestContainingPackage(t *testing.T) {
 	goroot := runtime.GOROOT()
 	gopath := filepath.SplitList(os.Getenv("GOPATH"))[0]
 
-	for _, test := range [][2]string{
+	tests := [][2]string{
 		{goroot + "/src/fmt/print.go", "fmt"},
 		{goroot + "/src/encoding/json/foo.go", "encoding/json"},
 		{goroot + "/src/encoding/missing/foo.go", "(not found)"},
 		{gopath + "/src/golang.org/x/tools/go/buildutil/util_test.go",
 			"golang.org/x/tools/go/buildutil"},
-		{gopath + "/src/vendor/golang.org/x/net/http2/hpack/hpack.go",
+	}
-			"vendor/golang.org/x/net/http2/hpack"},
+	// TODO(adonovan): simplify after Go 1.6.
-	} {
+	if buildutil.AllowVendor != 0 {
+		tests = append(tests, [2]string{
+			gopath + "/src/vendor/golang.org/x/net/http2/hpack/hpack.go",
+			"vendor/golang.org/x/net/http2/hpack",
+		})
+	}
+	for _, test := range tests {
 		file, want := test[0], test[1]
 		bp, err := buildutil.ContainingPackage(&build.Default, ".", file)
 		got := bp.ImportPath

go/loader/example15_test.go

@@ -0,0 +1,177 @@
+// Copyright 2015 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.
+
+// +build go1.5,!go1.6
+// +build !windows
+
+package loader_test
+
+import (
+	"fmt"
+	"go/token"
+	"log"
+	"path/filepath"
+	"runtime"
+	"sort"
+	"strings"
+
+	"golang.org/x/tools/go/loader"
+)
+
+func printProgram(prog *loader.Program) {
+	// Created packages are the initial packages specified by a call
+	// to CreateFromFilenames or CreateFromFiles.
+	var names []string
+	for _, info := range prog.Created {
+		names = append(names, info.Pkg.Path())
+	}
+	fmt.Printf("created: %s\n", names)
+
+	// Imported packages are the initial packages specified by a
+	// call to Import or ImportWithTests.
+	names = nil
+	for _, info := range prog.Imported {
+		if strings.Contains(info.Pkg.Path(), "internal") {
+			continue // skip, to reduce fragility
+		}
+		names = append(names, info.Pkg.Path())
+	}
+	sort.Strings(names)
+	fmt.Printf("imported: %s\n", names)
+
+	// InitialPackages contains the union of created and imported.
+	names = nil
+	for _, info := range prog.InitialPackages() {
+		names = append(names, info.Pkg.Path())
+	}
+	sort.Strings(names)
+	fmt.Printf("initial: %s\n", names)
+
+	// AllPackages contains all initial packages and their dependencies.
+	names = nil
+	for pkg := range prog.AllPackages {
+		names = append(names, pkg.Path())
+	}
+	sort.Strings(names)
+	fmt.Printf("all: %s\n", names)
+}
+
+func printFilenames(fset *token.FileSet, info *loader.PackageInfo) {
+	var names []string
+	for _, f := range info.Files {
+		names = append(names, filepath.Base(fset.File(f.Pos()).Name()))
+	}
+	fmt.Printf("%s.Files: %s\n", info.Pkg.Path(), names)
+}
+
+// This example loads a set of packages and all of their dependencies
+// from a typical command-line.  FromArgs parses a command line and
+// makes calls to the other methods of Config shown in the examples that
+// follow.
+func ExampleConfig_FromArgs() {
+	args := []string{"mytool", "unicode/utf8", "errors", "runtime", "--", "foo", "bar"}
+	const wantTests = false
+
+	var conf loader.Config
+	rest, err := conf.FromArgs(args[1:], wantTests)
+	prog, err := conf.Load()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	fmt.Printf("rest: %s\n", rest)
+	printProgram(prog)
+	// Output:
+	// rest: [foo bar]
+	// created: []
+	// imported: [errors runtime unicode/utf8]
+	// initial: [errors runtime unicode/utf8]
+	// all: [errors runtime unicode/utf8]
+}
+
+// This example creates and type-checks a single package (without tests)
+// from a list of filenames, and loads all of its dependencies.
+func ExampleConfig_CreateFromFilenames() {
+	var conf loader.Config
+	filename := filepath.Join(runtime.GOROOT(), "src/container/heap/heap.go")
+	conf.CreateFromFilenames("container/heap", filename)
+	prog, err := conf.Load()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	printProgram(prog)
+	// Output:
+	// created: [container/heap]
+	// imported: []
+	// initial: [container/heap]
+	// all: [container/heap sort]
+}
+
+// In the examples below, for stability, the chosen packages are
+// relatively small, platform-independent, and low-level (and thus
+// infrequently changing).
+// The strconv package has internal and external tests.
+
+const hello = `package main
+
+import "fmt"
+
+func main() {
+	fmt.Println("Hello, world.")
+}
+`
+
+// This example creates and type-checks a package from a list of
+// already-parsed files, and loads all its dependencies.
+func ExampleConfig_CreateFromFiles() {
+	var conf loader.Config
+	f, err := conf.ParseFile("hello.go", hello)
+	if err != nil {
+		log.Fatal(err)
+	}
+	conf.CreateFromFiles("hello", f)
+	prog, err := conf.Load()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	printProgram(prog)
+	printFilenames(prog.Fset, prog.Package("strconv"))
+	// Output:
+	// created: [hello]
+	// imported: []
+	// initial: [hello]
+	// all: [errors fmt hello io math os reflect runtime strconv sync sync/atomic syscall time unicode/utf8]
+	// strconv.Files: [atob.go atof.go atoi.go decimal.go doc.go extfloat.go ftoa.go isprint.go itoa.go quote.go]
+}
+
+// This example imports three packages, including the tests for one of
+// them, and loads all their dependencies.
+func ExampleConfig_Import() {
+	// ImportWithTest("strconv") causes strconv to include
+	// internal_test.go, and creates an external test package,
+	// strconv_test.
+	// (Compare with the example of CreateFromFiles.)
+
+	var conf loader.Config
+	conf.Import("unicode/utf8")
+	conf.Import("errors")
+	conf.ImportWithTests("strconv")
+	prog, err := conf.Load()
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	printProgram(prog)
+	printFilenames(prog.Fset, prog.Package("strconv"))
+	printFilenames(prog.Fset, prog.Package("strconv_test"))
+	// Output:
+	// created: [strconv_test]
+	// imported: [errors strconv unicode/utf8]
+	// initial: [errors strconv strconv_test unicode/utf8]
+	// all: [bufio bytes errors flag fmt io log math math/rand os reflect runtime runtime/pprof runtime/trace sort strconv strconv_test strings sync sync/atomic syscall testing text/tabwriter time unicode unicode/utf8]
+	// strconv.Files: [atob.go atof.go atoi.go decimal.go doc.go extfloat.go ftoa.go isprint.go itoa.go quote.go internal_test.go]
+	// strconv_test.Files: [atob_test.go atof_test.go atoi_test.go decimal_test.go example_test.go fp_test.go ftoa_test.go itoa_test.go quote_test.go strconv_test.go]
+}

go/loader/example_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build go1.5
+// +build go1.6
 // +build !windows
 
 package loader_test
@@ -14,6 +14,7 @@ import (
 	"path/filepath"
 	"runtime"
 	"sort"
+	"strings"
 
 	"golang.org/x/tools/go/loader"
 )
@@ -31,6 +32,9 @@ func printProgram(prog *loader.Program) {
 	// call to Import or ImportWithTests.
 	names = nil
 	for _, info := range prog.Imported {
+		if strings.Contains(info.Pkg.Path(), "internal") {
+			continue // skip, to reduce fragility
+		}
 		names = append(names, info.Pkg.Path())
 	}
 	sort.Strings(names)

go/loader/loader_test.go

@@ -394,6 +394,11 @@ func TestCwd(t *testing.T) {
 }
 
 func TestLoad_vendor(t *testing.T) {
+	if buildutil.AllowVendor == 0 {
+		// Vendoring requires Go 1.6.
+		// TODO(adonovan): delete in due course.
+		t.Skip()
+	}
 	pkgs := map[string]string{
 		"a":          `package a; import _ "x"`,
 		"a/vendor":   ``, // mkdir a/vendor