microfactory/microfactory_test.go - platform/build/blueprint - Git at Google

 // Copyright 2017 Google Inc. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 package microfactory

 import (
 	"flag"
 	"io/ioutil"
 	"os"
 	"path/filepath"
 	"reflect"
 	"runtime"
 	"testing"
 	"time"
 )

 func TestSimplePackagePathMap(t *testing.T) {
 	t.Parallel()

 	pkgMap := pkgPathMappingVar{&Config{}}
 	flags := flag.NewFlagSet("", flag.ContinueOnError)
 	flags.Var(&pkgMap, "m", "")
 	err := flags.Parse([]string{
 		"-m", "android/soong=build/soong/",
 		"-m", "github.com/google/blueprint/=build/blueprint",
 	})
 	if err != nil {
 		t.Fatal(err)
 	}

 	compare := func(got, want interface{}) {
 		if !reflect.DeepEqual(got, want) {
 			t.Errorf("Unexpected values in .pkgs:\nwant: %v\n got: %v",
 				want, got)
 		}
 	}

 	wantPkgs := []string{"android/soong", "github.com/google/blueprint"}
 	compare(pkgMap.pkgs, wantPkgs)
 	compare(pkgMap.paths[wantPkgs[0]], "build/soong")
 	compare(pkgMap.paths[wantPkgs[1]], "build/blueprint")

 	got, ok, err := pkgMap.Path("android/soong/ui/test")
 	if err != nil {
 		t.Error("Unexpected error in pkgMap.Path(soong):", err)
 	} else if !ok {
 		t.Error("Expected a result from pkgMap.Path(soong)")
 	} else {
 		compare(got, "build/soong/ui/test")
 	}

 	got, ok, err = pkgMap.Path("github.com/google/blueprint")
 	if err != nil {
 		t.Error("Unexpected error in pkgMap.Path(blueprint):", err)
 	} else if !ok {
 		t.Error("Expected a result from pkgMap.Path(blueprint)")
 	} else {
 		compare(got, "build/blueprint")
 	}
 }

 func TestBadPackagePathMap(t *testing.T) {
 	t.Parallel()

 	pkgMap := pkgPathMappingVar{&Config{}}
 	if _, _, err := pkgMap.Path("testing"); err == nil {
 		t.Error("Expected error if no maps are specified")
 	}
 	if err := pkgMap.Set(""); err == nil {
 		t.Error("Expected error with blank argument, but none returned")
 	}
 	if err := pkgMap.Set("a=a"); err != nil {
 		t.Errorf("Unexpected error: %v", err)
 	}
 	if err := pkgMap.Set("a=b"); err == nil {
 		t.Error("Expected error with duplicate package prefix, but none returned")
 	}
 	if _, ok, err := pkgMap.Path("testing"); err != nil {
 		t.Errorf("Unexpected error: %v", err)
 	} else if ok {
 		t.Error("Expected testing to be consider in the stdlib")
 	}
 }

 // TestSingleBuild ensures that just a basic build works.
 func TestSingleBuild(t *testing.T) {
 	t.Parallel()

 	setupDir(t, func(config *Config, dir string, loadPkg loadPkgFunc) {
 		// The output binary
 		out := filepath.Join(dir, "out", "test")

 		pkg := loadPkg()

 		if err := pkg.Compile(config, filepath.Join(dir, "out")); err != nil {
 			t.Fatal("Got error when compiling:", err)
 		}

 		if err := pkg.Link(config, out); err != nil {
 			t.Fatal("Got error when linking:", err)
 		}

 		if _, err := os.Stat(out); err != nil {
 			t.Error("Cannot stat output:", err)
 		}
 	})
 }

 // testBuildAgain triggers two builds, running the modify function in between
 // each build. It verifies that the second build did or did not actually need
 // to rebuild anything based on the shouldRebuild argument.
 func testBuildAgain(t *testing.T,
 	shouldRecompile, shouldRelink bool,
 	modify func(config *Config, dir string, loadPkg loadPkgFunc),
 	after func(pkg *GoPackage)) {

 	t.Parallel()

 	setupDir(t, func(config *Config, dir string, loadPkg loadPkgFunc) {
 		// The output binary
 		out := filepath.Join(dir, "out", "test")

 		pkg := loadPkg()

 		if err := pkg.Compile(config, filepath.Join(dir, "out")); err != nil {
 			t.Fatal("Got error when compiling:", err)
 		}

 		if err := pkg.Link(config, out); err != nil {
 			t.Fatal("Got error when linking:", err)
 		}

 		var firstTime time.Time
 		if stat, err := os.Stat(out); err == nil {
 			firstTime = stat.ModTime()
 		} else {
 			t.Fatal("Failed to stat output file:", err)
 		}

 		// mtime on HFS+ (the filesystem on darwin) are stored with 1
 		// second granularity, so the timestamp checks will fail unless
 		// we wait at least a second. Sleeping 1.1s to be safe.
 		if runtime.GOOS == "darwin" {
 			time.Sleep(1100 * time.Millisecond)
 		}

 		modify(config, dir, loadPkg)

 		pkg = loadPkg()

 		if err := pkg.Compile(config, filepath.Join(dir, "out")); err != nil {
 			t.Fatal("Got error when compiling:", err)
 		}
 		if shouldRecompile {
 			if !pkg.rebuilt {
 				t.Fatal("Package should have recompiled, but was not recompiled.")
 			}
 		} else {
 			if pkg.rebuilt {
 				t.Fatal("Package should not have needed to be recompiled, but was recompiled.")
 			}
 		}

 		if err := pkg.Link(config, out); err != nil {
 			t.Fatal("Got error while linking:", err)
 		}
 		if shouldRelink {
 			if !pkg.rebuilt {
 				t.Error("Package should have relinked, but was not relinked.")
 			}
 		} else {
 			if pkg.rebuilt {
 				t.Error("Package should not have needed to be relinked, but was relinked.")
 			}
 		}

 		if stat, err := os.Stat(out); err == nil {
 			if shouldRelink {
 				if stat.ModTime() == firstTime {
 					t.Error("Output timestamp should be different, but both were", firstTime)
 				}
 			} else {
 				if stat.ModTime() != firstTime {
 					t.Error("Output timestamp should be the same.")
 					t.Error(" first:", firstTime)
 					t.Error("second:", stat.ModTime())
 				}
 			}
 		} else {
 			t.Fatal("Failed to stat output file:", err)
 		}

 		after(pkg)
 	})
 }

 // TestRebuildAfterNoChanges ensures that we don't rebuild if nothing
 // changes
 func TestRebuildAfterNoChanges(t *testing.T) {
 	testBuildAgain(t, false, false, func(config *Config, dir string, loadPkg loadPkgFunc) {}, func(pkg *GoPackage) {})
 }

 // TestRebuildAfterTimestamp ensures that we don't rebuild because
 // timestamps of important files have changed. We should only rebuild if the
 // content hashes are different.
 func TestRebuildAfterTimestampChange(t *testing.T) {
 	testBuildAgain(t, false, false, func(config *Config, dir string, loadPkg loadPkgFunc) {
 		// Ensure that we've spent some amount of time asleep
 		time.Sleep(100 * time.Millisecond)

 		newTime := time.Now().Local()
 		os.Chtimes(filepath.Join(dir, "test.fact"), newTime, newTime)
 		os.Chtimes(filepath.Join(dir, "main/main.go"), newTime, newTime)
 		os.Chtimes(filepath.Join(dir, "a/a.go"), newTime, newTime)
 		os.Chtimes(filepath.Join(dir, "a/b.go"), newTime, newTime)
 		os.Chtimes(filepath.Join(dir, "b/a.go"), newTime, newTime)
 	}, func(pkg *GoPackage) {})
 }

 // TestRebuildAfterGoChange ensures that we rebuild after a content change
 // to a package's go file.
 func TestRebuildAfterGoChange(t *testing.T) {
 	testBuildAgain(t, true, true, func(config *Config, dir string, loadPkg loadPkgFunc) {
 		if err := ioutil.WriteFile(filepath.Join(dir, "a", "a.go"), []byte(go_a_a+"\n"), 0666); err != nil {
 			t.Fatal("Error writing a/a.go:", err)
 		}
 	}, func(pkg *GoPackage) {
 		if !pkg.directDeps[0].rebuilt {
 			t.Fatal("android/soong/a should have rebuilt")
 		}
 		if !pkg.directDeps[1].rebuilt {
 			t.Fatal("android/soong/b should have rebuilt")
 		}
 	})
 }

 // TestRebuildAfterMainChange ensures that we don't rebuild any dependencies
 // if only the main package's go files are touched.
 func TestRebuildAfterMainChange(t *testing.T) {
 	testBuildAgain(t, true, true, func(config *Config, dir string, loadPkg loadPkgFunc) {
 		if err := ioutil.WriteFile(filepath.Join(dir, "main", "main.go"), []byte(go_main_main+"\n"), 0666); err != nil {
 			t.Fatal("Error writing main/main.go:", err)
 		}
 	}, func(pkg *GoPackage) {
 		if pkg.directDeps[0].rebuilt {
 			t.Fatal("android/soong/a should not have rebuilt")
 		}
 		if pkg.directDeps[1].rebuilt {
 			t.Fatal("android/soong/b should not have rebuilt")
 		}
 	})
 }

 // TestRebuildAfterRemoveOut ensures that we rebuild if the output file is
 // missing, even if everything else doesn't need rebuilding.
 func TestRebuildAfterRemoveOut(t *testing.T) {
 	testBuildAgain(t, false, true, func(config *Config, dir string, loadPkg loadPkgFunc) {
 		if err := os.Remove(filepath.Join(dir, "out", "test")); err != nil {
 			t.Fatal("Failed to remove output:", err)
 		}
 	}, func(pkg *GoPackage) {})
 }

 // TestRebuildAfterPartialBuild ensures that even if the build was interrupted
 // between the recompile and relink stages, we'll still relink when we run again.
 func TestRebuildAfterPartialBuild(t *testing.T) {
 	testBuildAgain(t, false, true, func(config *Config, dir string, loadPkg loadPkgFunc) {
 		if err := ioutil.WriteFile(filepath.Join(dir, "main", "main.go"), []byte(go_main_main+"\n"), 0666); err != nil {
 			t.Fatal("Error writing main/main.go:", err)
 		}

 		pkg := loadPkg()

 		if err := pkg.Compile(config, filepath.Join(dir, "out")); err != nil {
 			t.Fatal("Got error when compiling:", err)
 		}
 		if !pkg.rebuilt {
 			t.Fatal("Package should have recompiled, but was not recompiled.")
 		}
 	}, func(pkg *GoPackage) {})
 }

 // BenchmarkInitialBuild computes how long a clean build takes (for tiny test
 // inputs).
 func BenchmarkInitialBuild(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		setupDir(b, func(config *Config, dir string, loadPkg loadPkgFunc) {
 			pkg := loadPkg()
 			if err := pkg.Compile(config, filepath.Join(dir, "out")); err != nil {
 				b.Fatal("Got error when compiling:", err)
 			}

 			if err := pkg.Link(config, filepath.Join(dir, "out", "test")); err != nil {
 				b.Fatal("Got error when linking:", err)
 			}
 		})
 	}
 }

 // BenchmarkMinIncrementalBuild computes how long an incremental build that
 // doesn't actually need to build anything takes.
 func BenchmarkMinIncrementalBuild(b *testing.B) {
 	setupDir(b, func(config *Config, dir string, loadPkg loadPkgFunc) {
 		pkg := loadPkg()

 		if err := pkg.Compile(config, filepath.Join(dir, "out")); err != nil {
 			b.Fatal("Got error when compiling:", err)
 		}

 		if err := pkg.Link(config, filepath.Join(dir, "out", "test")); err != nil {
 			b.Fatal("Got error when linking:", err)
 		}

 		b.ResetTimer()

 		for i := 0; i < b.N; i++ {
 			pkg := loadPkg()

 			if err := pkg.Compile(config, filepath.Join(dir, "out")); err != nil {
 				b.Fatal("Got error when compiling:", err)
 			}

 			if err := pkg.Link(config, filepath.Join(dir, "out", "test")); err != nil {
 				b.Fatal("Got error when linking:", err)
 			}

 			if pkg.rebuilt {
 				b.Fatal("Should not have rebuilt anything")
 			}
 		}
 	})
 }

 ///////////////////////////////////////////////////////
 // Templates used to create fake compilable packages //
 ///////////////////////////////////////////////////////

 const go_main_main = `
 package main
 import (
 	"fmt"
 	"android/soong/a"
 	"android/soong/b"
 )
 func main() {
 	fmt.Println(a.Stdout, b.Stdout)
 }
 `

 const go_a_a = `
 package a
 import "os"
 var Stdout = os.Stdout
 `

 const go_a_b = `
 package a
 `

 const go_b_a = `
 package b
 import "android/soong/a"
 var Stdout = a.Stdout
 `

 type T interface {
 	Fatal(args ...interface{})
 	Fatalf(format string, args ...interface{})
 }

 type loadPkgFunc func() *GoPackage

 func setupDir(t T, test func(config *Config, dir string, loadPkg loadPkgFunc)) {
 	dir, err := ioutil.TempDir("", "test")
 	if err != nil {
 		t.Fatalf("Error creating temporary directory: %#v", err)
 	}
 	defer os.RemoveAll(dir)

 	writeFile := func(name, contents string) {
 		if err := ioutil.WriteFile(filepath.Join(dir, name), []byte(contents), 0666); err != nil {
 			t.Fatalf("Error writing %q: %#v", name, err)
 		}
 	}
 	mkdir := func(name string) {
 		if err := os.Mkdir(filepath.Join(dir, name), 0777); err != nil {
 			t.Fatalf("Error creating %q directory: %#v", name, err)
 		}
 	}
 	mkdir("main")
 	mkdir("a")
 	mkdir("b")
 	writeFile("main/main.go", go_main_main)
 	writeFile("a/a.go", go_a_a)
 	writeFile("a/b.go", go_a_b)
 	writeFile("b/a.go", go_b_a)

 	config := &Config{}
 	config.Map("android/soong", dir)

 	loadPkg := func() *GoPackage {
 		pkg := &GoPackage{
 			Name: "main",
 		}
 		if err := pkg.FindDeps(config, filepath.Join(dir, "main")); err != nil {
 			t.Fatalf("Error finding deps: %v", err)
 		}
 		return pkg
 	}

 	test(config, dir, loadPkg)
 }
	// Copyright 2017 Google Inc. All rights reserved.
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	package microfactory

	import (
	"flag"
	"io/ioutil"
	"os"
	"path/filepath"
	"reflect"
	"runtime"
	"testing"
	"time"
	)

	func TestSimplePackagePathMap(t *testing.T) {
	t.Parallel()

	pkgMap := pkgPathMappingVar{&Config{}}
	flags := flag.NewFlagSet("", flag.ContinueOnError)
	flags.Var(&pkgMap, "m", "")
	err := flags.Parse([]string{
	"-m", "android/soong=build/soong/",
	"-m", "github.com/google/blueprint/=build/blueprint",
	})
	if err != nil {
	t.Fatal(err)
	}

	compare := func(got, want interface{}) {
	if !reflect.DeepEqual(got, want) {
	t.Errorf("Unexpected values in .pkgs:\nwant: %v\n got: %v",
	want, got)
	}
	}

	wantPkgs := []string{"android/soong", "github.com/google/blueprint"}
	compare(pkgMap.pkgs, wantPkgs)
	compare(pkgMap.paths[wantPkgs[0]], "build/soong")
	compare(pkgMap.paths[wantPkgs[1]], "build/blueprint")

	got, ok, err := pkgMap.Path("android/soong/ui/test")
	if err != nil {
	t.Error("Unexpected error in pkgMap.Path(soong):", err)
	} else if !ok {
	t.Error("Expected a result from pkgMap.Path(soong)")
	} else {
	compare(got, "build/soong/ui/test")
	}

	got, ok, err = pkgMap.Path("github.com/google/blueprint")
	if err != nil {
	t.Error("Unexpected error in pkgMap.Path(blueprint):", err)
	} else if !ok {
	t.Error("Expected a result from pkgMap.Path(blueprint)")
	} else {
	compare(got, "build/blueprint")
	}
	}

	func TestBadPackagePathMap(t *testing.T) {
	t.Parallel()

	pkgMap := pkgPathMappingVar{&Config{}}
	if _, _, err := pkgMap.Path("testing"); err == nil {
	t.Error("Expected error if no maps are specified")
	}
	if err := pkgMap.Set(""); err == nil {
	t.Error("Expected error with blank argument, but none returned")
	}
	if err := pkgMap.Set("a=a"); err != nil {
	t.Errorf("Unexpected error: %v", err)
	}
	if err := pkgMap.Set("a=b"); err == nil {
	t.Error("Expected error with duplicate package prefix, but none returned")
	}
	if _, ok, err := pkgMap.Path("testing"); err != nil {
	t.Errorf("Unexpected error: %v", err)
	} else if ok {
	t.Error("Expected testing to be consider in the stdlib")
	}
	}

	// TestSingleBuild ensures that just a basic build works.
	func TestSingleBuild(t *testing.T) {
	t.Parallel()

	setupDir(t, func(config *Config, dir string, loadPkg loadPkgFunc) {
	// The output binary
	out := filepath.Join(dir, "out", "test")

	pkg := loadPkg()

	if err := pkg.Compile(config, filepath.Join(dir, "out")); err != nil {
	t.Fatal("Got error when compiling:", err)
	}

	if err := pkg.Link(config, out); err != nil {
	t.Fatal("Got error when linking:", err)
	}

	if _, err := os.Stat(out); err != nil {
	t.Error("Cannot stat output:", err)
	}
	})
	}

	// testBuildAgain triggers two builds, running the modify function in between
	// each build. It verifies that the second build did or did not actually need
	// to rebuild anything based on the shouldRebuild argument.
	func testBuildAgain(t *testing.T,
	shouldRecompile, shouldRelink bool,
	modify func(config *Config, dir string, loadPkg loadPkgFunc),
	after func(pkg *GoPackage)) {

	t.Parallel()

	setupDir(t, func(config *Config, dir string, loadPkg loadPkgFunc) {
	// The output binary
	out := filepath.Join(dir, "out", "test")

	pkg := loadPkg()

	if err := pkg.Compile(config, filepath.Join(dir, "out")); err != nil {
	t.Fatal("Got error when compiling:", err)
	}

	if err := pkg.Link(config, out); err != nil {
	t.Fatal("Got error when linking:", err)
	}

	var firstTime time.Time
	if stat, err := os.Stat(out); err == nil {
	firstTime = stat.ModTime()
	} else {
	t.Fatal("Failed to stat output file:", err)
	}

	// mtime on HFS+ (the filesystem on darwin) are stored with 1
	// second granularity, so the timestamp checks will fail unless
	// we wait at least a second. Sleeping 1.1s to be safe.
	if runtime.GOOS == "darwin" {
	time.Sleep(1100 * time.Millisecond)
	}

	modify(config, dir, loadPkg)

	pkg = loadPkg()

	if err := pkg.Compile(config, filepath.Join(dir, "out")); err != nil {
	t.Fatal("Got error when compiling:", err)
	}
	if shouldRecompile {
	if !pkg.rebuilt {
	t.Fatal("Package should have recompiled, but was not recompiled.")
	}
	} else {
	if pkg.rebuilt {
	t.Fatal("Package should not have needed to be recompiled, but was recompiled.")
	}
	}

	if err := pkg.Link(config, out); err != nil {
	t.Fatal("Got error while linking:", err)
	}
	if shouldRelink {
	if !pkg.rebuilt {
	t.Error("Package should have relinked, but was not relinked.")
	}
	} else {
	if pkg.rebuilt {
	t.Error("Package should not have needed to be relinked, but was relinked.")
	}
	}

	if stat, err := os.Stat(out); err == nil {
	if shouldRelink {
	if stat.ModTime() == firstTime {
	t.Error("Output timestamp should be different, but both were", firstTime)
	}
	} else {
	if stat.ModTime() != firstTime {
	t.Error("Output timestamp should be the same.")
	t.Error(" first:", firstTime)
	t.Error("second:", stat.ModTime())
	}
	}
	} else {
	t.Fatal("Failed to stat output file:", err)
	}

	after(pkg)
	})
	}

	// TestRebuildAfterNoChanges ensures that we don't rebuild if nothing
	// changes
	func TestRebuildAfterNoChanges(t *testing.T) {
	testBuildAgain(t, false, false, func(config Config, dir string, loadPkg loadPkgFunc) {}, func(pkg GoPackage) {})
	}

	// TestRebuildAfterTimestamp ensures that we don't rebuild because
	// timestamps of important files have changed. We should only rebuild if the
	// content hashes are different.
	func TestRebuildAfterTimestampChange(t *testing.T) {
	testBuildAgain(t, false, false, func(config *Config, dir string, loadPkg loadPkgFunc) {
	// Ensure that we've spent some amount of time asleep
	time.Sleep(100 * time.Millisecond)

	newTime := time.Now().Local()
	os.Chtimes(filepath.Join(dir, "test.fact"), newTime, newTime)
	os.Chtimes(filepath.Join(dir, "main/main.go"), newTime, newTime)
	os.Chtimes(filepath.Join(dir, "a/a.go"), newTime, newTime)
	os.Chtimes(filepath.Join(dir, "a/b.go"), newTime, newTime)
	os.Chtimes(filepath.Join(dir, "b/a.go"), newTime, newTime)
	}, func(pkg *GoPackage) {})
	}

	// TestRebuildAfterGoChange ensures that we rebuild after a content change
	// to a package's go file.
	func TestRebuildAfterGoChange(t *testing.T) {
	testBuildAgain(t, true, true, func(config *Config, dir string, loadPkg loadPkgFunc) {
	if err := ioutil.WriteFile(filepath.Join(dir, "a", "a.go"), []byte(go_a_a+"\n"), 0666); err != nil {
	t.Fatal("Error writing a/a.go:", err)
	}
	}, func(pkg *GoPackage) {
	if !pkg.directDeps[0].rebuilt {
	t.Fatal("android/soong/a should have rebuilt")
	}
	if !pkg.directDeps[1].rebuilt {
	t.Fatal("android/soong/b should have rebuilt")
	}
	})
	}

	// TestRebuildAfterMainChange ensures that we don't rebuild any dependencies
	// if only the main package's go files are touched.
	func TestRebuildAfterMainChange(t *testing.T) {
	testBuildAgain(t, true, true, func(config *Config, dir string, loadPkg loadPkgFunc) {
	if err := ioutil.WriteFile(filepath.Join(dir, "main", "main.go"), []byte(go_main_main+"\n"), 0666); err != nil {
	t.Fatal("Error writing main/main.go:", err)
	}
	}, func(pkg *GoPackage) {
	if pkg.directDeps[0].rebuilt {
	t.Fatal("android/soong/a should not have rebuilt")
	}
	if pkg.directDeps[1].rebuilt {
	t.Fatal("android/soong/b should not have rebuilt")
	}
	})
	}

	// TestRebuildAfterRemoveOut ensures that we rebuild if the output file is
	// missing, even if everything else doesn't need rebuilding.
	func TestRebuildAfterRemoveOut(t *testing.T) {
	testBuildAgain(t, false, true, func(config *Config, dir string, loadPkg loadPkgFunc) {
	if err := os.Remove(filepath.Join(dir, "out", "test")); err != nil {
	t.Fatal("Failed to remove output:", err)
	}
	}, func(pkg *GoPackage) {})
	}

	// TestRebuildAfterPartialBuild ensures that even if the build was interrupted
	// between the recompile and relink stages, we'll still relink when we run again.
	func TestRebuildAfterPartialBuild(t *testing.T) {
	testBuildAgain(t, false, true, func(config *Config, dir string, loadPkg loadPkgFunc) {
	if err := ioutil.WriteFile(filepath.Join(dir, "main", "main.go"), []byte(go_main_main+"\n"), 0666); err != nil {
	t.Fatal("Error writing main/main.go:", err)
	}

	pkg := loadPkg()

	if err := pkg.Compile(config, filepath.Join(dir, "out")); err != nil {
	t.Fatal("Got error when compiling:", err)
	}
	if !pkg.rebuilt {
	t.Fatal("Package should have recompiled, but was not recompiled.")
	}
	}, func(pkg *GoPackage) {})
	}

	// BenchmarkInitialBuild computes how long a clean build takes (for tiny test
	// inputs).
	func BenchmarkInitialBuild(b *testing.B) {
	for i := 0; i < b.N; i++ {
	setupDir(b, func(config *Config, dir string, loadPkg loadPkgFunc) {
	pkg := loadPkg()
	if err := pkg.Compile(config, filepath.Join(dir, "out")); err != nil {
	b.Fatal("Got error when compiling:", err)
	}

	if err := pkg.Link(config, filepath.Join(dir, "out", "test")); err != nil {
	b.Fatal("Got error when linking:", err)
	}
	})
	}
	}

	// BenchmarkMinIncrementalBuild computes how long an incremental build that
	// doesn't actually need to build anything takes.
	func BenchmarkMinIncrementalBuild(b *testing.B) {
	setupDir(b, func(config *Config, dir string, loadPkg loadPkgFunc) {
	pkg := loadPkg()

	if err := pkg.Compile(config, filepath.Join(dir, "out")); err != nil {
	b.Fatal("Got error when compiling:", err)
	}

	if err := pkg.Link(config, filepath.Join(dir, "out", "test")); err != nil {
	b.Fatal("Got error when linking:", err)
	}

	b.ResetTimer()

	for i := 0; i < b.N; i++ {
	pkg := loadPkg()

	if err := pkg.Compile(config, filepath.Join(dir, "out")); err != nil {
	b.Fatal("Got error when compiling:", err)
	}

	if err := pkg.Link(config, filepath.Join(dir, "out", "test")); err != nil {
	b.Fatal("Got error when linking:", err)
	}

	if pkg.rebuilt {
	b.Fatal("Should not have rebuilt anything")
	}
	}
	})
	}

	///////////////////////////////////////////////////////
	// Templates used to create fake compilable packages //
	///////////////////////////////////////////////////////

	const go_main_main = `
	package main
	import (
	"fmt"
	"android/soong/a"
	"android/soong/b"
	)
	func main() {
	fmt.Println(a.Stdout, b.Stdout)
	}
	`

	const go_a_a = `
	package a
	import "os"
	var Stdout = os.Stdout
	`

	const go_a_b = `
	package a
	`

	const go_b_a = `
	package b
	import "android/soong/a"
	var Stdout = a.Stdout
	`

	type T interface {
	Fatal(args ...interface{})
	Fatalf(format string, args ...interface{})
	}

	type loadPkgFunc func() *GoPackage

	func setupDir(t T, test func(config *Config, dir string, loadPkg loadPkgFunc)) {
	dir, err := ioutil.TempDir("", "test")
	if err != nil {
	t.Fatalf("Error creating temporary directory: %#v", err)
	}
	defer os.RemoveAll(dir)

	writeFile := func(name, contents string) {
	if err := ioutil.WriteFile(filepath.Join(dir, name), []byte(contents), 0666); err != nil {
	t.Fatalf("Error writing %q: %#v", name, err)
	}
	}
	mkdir := func(name string) {
	if err := os.Mkdir(filepath.Join(dir, name), 0777); err != nil {
	t.Fatalf("Error creating %q directory: %#v", name, err)
	}
	}
	mkdir("main")
	mkdir("a")
	mkdir("b")
	writeFile("main/main.go", go_main_main)
	writeFile("a/a.go", go_a_a)
	writeFile("a/b.go", go_a_b)
	writeFile("b/a.go", go_b_a)

	config := &Config{}
	config.Map("android/soong", dir)

	loadPkg := func() *GoPackage {
	pkg := &GoPackage{
	Name: "main",
	}
	if err := pkg.FindDeps(config, filepath.Join(dir, "main")); err != nil {
	t.Fatalf("Error finding deps: %v", err)
	}
	return pkg
	}

	test(config, dir, loadPkg)
	}