bp2build: add allowlist for package-level conversions.

This CL adds the support for specifying lists of directories in
build/soong/android/bazel.go, which are then written into
out/soong/bp2build/MANIFEST. Using this configuration,
modules/directories can either default to bp2build_available: true or
false, while still retaining the ability to opt-in or out at the module level.

It also ensures that ConvertWithBp2Build returns true iff the module
type has a registered bp2build converter.

Test: go tests
Test: demo.sh full
Test: TreeHugger presubmits for bp2build and mixed builds.

Change-Id: I0e0f6f4b1b2ec045f2f1c338f7084defc5d23a55

android/Android.bp

@@ -85,6 +85,7 @@ bootstrap_go_package {
         "androidmk_test.go",
         "apex_test.go",
         "arch_test.go",
+        "bazel_test.go",
         "config_test.go",
         "csuite_config_test.go",
         "depset_test.go",

android/bazel.go

@@ -32,7 +32,13 @@ type bazelModuleProperties struct {
 
 	// If true, bp2build will generate the converted Bazel target for this module. Note: this may
 	// cause a conflict due to the duplicate targets if label is also set.
-	Bp2build_available bool
+	//
+	// This is a bool pointer to support tristates: true, false, not set.
+	//
+	// To opt-in a module, set bazel_module: { bp2build_available: true }
+	// To opt-out a module, set bazel_module: { bp2build_available: false }
+	// To defer the default setting for the directory, do not set the value.
+	Bp2build_available *bool
 }
 
 // Properties contains common module properties for Bazel migration purposes.
@@ -54,9 +60,9 @@ type Bazelable interface {
 	HasHandcraftedLabel() bool
 	HandcraftedLabel() string
 	GetBazelLabel(ctx BazelConversionPathContext, module blueprint.Module) string
-	ConvertWithBp2build() bool
+	ConvertWithBp2build(ctx BazelConversionPathContext) bool
 	GetBazelBuildFileContents(c Config, path, name string) (string, error)
-	ConvertedToBazel() bool
+	ConvertedToBazel(ctx BazelConversionPathContext) bool
 }
 
 // BazelModule is a lightweight wrapper interface around Module for Bazel-convertible modules.
@@ -91,15 +97,91 @@ func (b *BazelModuleBase) GetBazelLabel(ctx BazelConversionPathContext, module b
 	if b.HasHandcraftedLabel() {
 		return b.HandcraftedLabel()
 	}
-	if b.ConvertWithBp2build() {
+	if b.ConvertWithBp2build(ctx) {
 		return bp2buildModuleLabel(ctx, module)
 	}
 	return "" // no label for unconverted module
 }
 
+// Configuration to decide if modules in a directory should default to true/false for bp2build_available
+type Bp2BuildConfig map[string]BazelConversionConfigEntry
+type BazelConversionConfigEntry int
+
+const (
+	// iota + 1 ensures that the int value is not 0 when used in the Bp2buildAllowlist map,
+	// which can also mean that the key doesn't exist in a lookup.
+
+	// all modules in this package and subpackages default to bp2build_available: true.
+	// allows modules to opt-out.
+	Bp2BuildDefaultTrueRecursively BazelConversionConfigEntry = iota + 1
+
+	// all modules in this package (not recursively) default to bp2build_available: false.
+	// allows modules to opt-in.
+	Bp2BuildDefaultFalse
+)
+
+var (
+	// Configure modules in these directories to enable bp2build_available: true or false by default.
+	bp2buildDefaultConfig = Bp2BuildConfig{
+		"bionic":                Bp2BuildDefaultTrueRecursively,
+		"system/core/libcutils": Bp2BuildDefaultTrueRecursively,
+		"system/logging/liblog": Bp2BuildDefaultTrueRecursively,
+	}
+)
+
 // ConvertWithBp2build returns whether the given BazelModuleBase should be converted with bp2build.
-func (b *BazelModuleBase) ConvertWithBp2build() bool {
+func (b *BazelModuleBase) ConvertWithBp2build(ctx BazelConversionPathContext) bool {
-	return b.bazelProperties.Bazel_module.Bp2build_available
+	// Ensure that the module type of this module has a bp2build converter. This
+	// prevents mixed builds from using auto-converted modules just by matching
+	// the package dir; it also has to have a bp2build mutator as well.
+	if ctx.Config().bp2buildModuleTypeConfig[ctx.ModuleType()] == false {
+		return false
+	}
+
+	packagePath := ctx.ModuleDir()
+	config := ctx.Config().bp2buildPackageConfig
+
+	// This is a tristate value: true, false, or unset.
+	propValue := b.bazelProperties.Bazel_module.Bp2build_available
+	if bp2buildDefaultTrueRecursively(packagePath, config) {
+		// Allow modules to explicitly opt-out.
+		return proptools.BoolDefault(propValue, true)
+	}
+
+	// Allow modules to explicitly opt-in.
+	return proptools.BoolDefault(propValue, false)
+}
+
+// bp2buildDefaultTrueRecursively checks that the package contains a prefix from the
+// set of package prefixes where all modules must be converted. That is, if the
+// package is x/y/z, and the list contains either x, x/y, or x/y/z, this function will
+// return true.
+//
+// However, if the package is x/y, and it matches a Bp2BuildDefaultFalse "x/y" entry
+// exactly, this module will return false early.
+//
+// This function will also return false if the package doesn't match anything in
+// the config.
+func bp2buildDefaultTrueRecursively(packagePath string, config Bp2BuildConfig) bool {
+	ret := false
+
+	if config[packagePath] == Bp2BuildDefaultFalse {
+		return false
+	}
+
+	packagePrefix := ""
+	// e.g. for x/y/z, iterate over x, x/y, then x/y/z, taking the final value from the allowlist.
+	for _, part := range strings.Split(packagePath, "/") {
+		packagePrefix += part
+		if config[packagePrefix] == Bp2BuildDefaultTrueRecursively {
+			// package contains this prefix and this prefix should convert all modules
+			return true
+		}
+		// Continue to the next part of the package dir.
+		packagePrefix += "/"
+	}
+
+	return ret
 }
 
 // GetBazelBuildFileContents returns the file contents of a hand-crafted BUILD file if available or
@@ -126,6 +208,6 @@ func (b *BazelModuleBase) GetBazelBuildFileContents(c Config, path, name string)
 
 // ConvertedToBazel returns whether this module has been converted to Bazel, whether automatically
 // or manually
-func (b *BazelModuleBase) ConvertedToBazel() bool {
+func (b *BazelModuleBase) ConvertedToBazel(ctx BazelConversionPathContext) bool {
-	return b.ConvertWithBp2build() || b.HasHandcraftedLabel()
+	return b.ConvertWithBp2build(ctx) || b.HasHandcraftedLabel()
 }

android/bazel_test.go

@@ -0,0 +1,134 @@
+// Copyright 2021 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 android
+
+import "testing"
+
+func TestConvertAllModulesInPackage(t *testing.T) {
+	testCases := []struct {
+		prefixes   Bp2BuildConfig
+		packageDir string
+	}{
+		{
+			prefixes: Bp2BuildConfig{
+				"a": Bp2BuildDefaultTrueRecursively,
+			},
+			packageDir: "a",
+		},
+		{
+			prefixes: Bp2BuildConfig{
+				"a/b": Bp2BuildDefaultTrueRecursively,
+			},
+			packageDir: "a/b",
+		},
+		{
+			prefixes: Bp2BuildConfig{
+				"a/b":   Bp2BuildDefaultTrueRecursively,
+				"a/b/c": Bp2BuildDefaultTrueRecursively,
+			},
+			packageDir: "a/b",
+		},
+		{
+			prefixes: Bp2BuildConfig{
+				"a":     Bp2BuildDefaultTrueRecursively,
+				"d/e/f": Bp2BuildDefaultTrueRecursively,
+			},
+			packageDir: "a/b",
+		},
+		{
+			prefixes: Bp2BuildConfig{
+				"a":     Bp2BuildDefaultFalse,
+				"a/b":   Bp2BuildDefaultTrueRecursively,
+				"a/b/c": Bp2BuildDefaultFalse,
+			},
+			packageDir: "a/b",
+		},
+		{
+			prefixes: Bp2BuildConfig{
+				"a":     Bp2BuildDefaultTrueRecursively,
+				"a/b":   Bp2BuildDefaultFalse,
+				"a/b/c": Bp2BuildDefaultTrueRecursively,
+			},
+			packageDir: "a",
+		},
+	}
+
+	for _, test := range testCases {
+		if !bp2buildDefaultTrueRecursively(test.packageDir, test.prefixes) {
+			t.Errorf("Expected to convert all modules in %s based on %v, but failed.", test.packageDir, test.prefixes)
+		}
+	}
+}
+
+func TestModuleOptIn(t *testing.T) {
+	testCases := []struct {
+		prefixes   Bp2BuildConfig
+		packageDir string
+	}{
+		{
+			prefixes: Bp2BuildConfig{
+				"a/b": Bp2BuildDefaultFalse,
+			},
+			packageDir: "a/b",
+		},
+		{
+			prefixes: Bp2BuildConfig{
+				"a":   Bp2BuildDefaultFalse,
+				"a/b": Bp2BuildDefaultTrueRecursively,
+			},
+			packageDir: "a",
+		},
+		{
+			prefixes: Bp2BuildConfig{
+				"a/b": Bp2BuildDefaultTrueRecursively,
+			},
+			packageDir: "a", // opt-in by default
+		},
+		{
+			prefixes: Bp2BuildConfig{
+				"a/b/c": Bp2BuildDefaultTrueRecursively,
+			},
+			packageDir: "a/b",
+		},
+		{
+			prefixes: Bp2BuildConfig{
+				"a":     Bp2BuildDefaultTrueRecursively,
+				"d/e/f": Bp2BuildDefaultTrueRecursively,
+			},
+			packageDir: "foo/bar",
+		},
+		{
+			prefixes: Bp2BuildConfig{
+				"a":     Bp2BuildDefaultTrueRecursively,
+				"a/b":   Bp2BuildDefaultFalse,
+				"a/b/c": Bp2BuildDefaultTrueRecursively,
+			},
+			packageDir: "a/b",
+		},
+		{
+			prefixes: Bp2BuildConfig{
+				"a":     Bp2BuildDefaultFalse,
+				"a/b":   Bp2BuildDefaultTrueRecursively,
+				"a/b/c": Bp2BuildDefaultFalse,
+			},
+			packageDir: "a",
+		},
+	}
+
+	for _, test := range testCases {
+		if bp2buildDefaultTrueRecursively(test.packageDir, test.prefixes) {
+			t.Errorf("Expected to allow module opt-in in %s based on %v, but failed.", test.packageDir, test.prefixes)
+		}
+	}
+}

android/config.go

@@ -140,6 +140,9 @@ type config struct {
 	fs         pathtools.FileSystem
 	mockBpList string
 
+	bp2buildPackageConfig    Bp2BuildConfig
+	bp2buildModuleTypeConfig map[string]bool
+
 	// If testAllowNonExistentPaths is true then PathForSource and PathForModuleSrc won't error
 	// in tests when a path doesn't exist.
 	TestAllowNonExistentPaths bool
@@ -281,6 +284,8 @@ func TestConfig(buildDir string, env map[string]string, bp string, fs map[string
 
 	config.mockFileSystem(bp, fs)
 
+	config.bp2buildModuleTypeConfig = map[string]bool{}
+
 	return Config{config}
 }
 
@@ -452,6 +457,8 @@ func NewConfig(srcDir, buildDir string, moduleListFile string) (Config, error) {
 			Bool(config.productVariables.ClangCoverage))
 
 	config.BazelContext, err = NewBazelContext(config)
+	config.bp2buildPackageConfig = bp2buildDefaultConfig
+	config.bp2buildModuleTypeConfig = make(map[string]bool)
 
 	return Config{config}, err
 }

android/filegroup.go

@@ -53,7 +53,7 @@ func (bfg *bazelFilegroup) GenerateAndroidBuildActions(ctx ModuleContext) {}
 
 func FilegroupBp2Build(ctx TopDownMutatorContext) {
 	fg, ok := ctx.Module().(*fileGroup)
-	if !ok || !fg.ConvertWithBp2build() {
+	if !ok || !fg.ConvertWithBp2build(ctx) {
 		return
 	}
 

android/mutator.go

@@ -226,7 +226,7 @@ func FinalDepsMutators(f RegisterMutatorFunc) {
 
 var bp2buildPreArchMutators = []RegisterMutatorFunc{}
 var bp2buildDepsMutators = []RegisterMutatorFunc{}
-var bp2buildMutators = []RegisterMutatorFunc{}
+var bp2buildMutators = map[string]RegisterMutatorFunc{}
 
 // RegisterBp2BuildMutator registers specially crafted mutators for
 // converting Blueprint/Android modules into special modules that can
@@ -237,7 +237,7 @@ func RegisterBp2BuildMutator(moduleType string, m func(TopDownMutatorContext)) {
 	f := func(ctx RegisterMutatorsContext) {
 		ctx.TopDown(moduleType, m)
 	}
-	bp2buildMutators = append(bp2buildMutators, f)
+	bp2buildMutators[moduleType] = f
 }
 
 // PreArchBp2BuildMutators adds mutators to be register for converting Android Blueprint modules

android/paths.go

@@ -340,6 +340,7 @@ type BazelConversionPathContext interface {
 
 	GetDirectDep(name string) (blueprint.Module, blueprint.DependencyTag)
 	Module() Module
+	ModuleType() string
 	OtherModuleName(m blueprint.Module) string
 	OtherModuleDir(m blueprint.Module) string
 }
@@ -450,7 +451,7 @@ func bazelModuleLabel(ctx BazelConversionPathContext, module blueprint.Module, t
 	// TODO(b/165114590): Convert tag (":name{.tag}") to corresponding Bazel implicit output targets.
 	b, ok := module.(Bazelable)
 	// TODO(b/181155349): perhaps return an error here if the module can't be/isn't being converted
-	if !ok || !b.ConvertedToBazel() {
+	if !ok || !b.ConvertedToBazel(ctx) {
 		return bp2buildModuleLabel(ctx, module)
 	}
 	return b.GetBazelLabel(ctx, module)

android/register.go

@@ -174,7 +174,13 @@ func (ctx *Context) RegisterForBazelConversion() {
 		t.register(ctx)
 	}
 
-	RegisterMutatorsForBazelConversion(ctx, bp2buildPreArchMutators, bp2buildDepsMutators, bp2buildMutators)
+	bp2buildMutatorList := []RegisterMutatorFunc{}
+	for t, f := range bp2buildMutators {
+		ctx.config.bp2buildModuleTypeConfig[t] = true
+		bp2buildMutatorList = append(bp2buildMutatorList, f)
+	}
+
+	RegisterMutatorsForBazelConversion(ctx, bp2buildPreArchMutators, bp2buildDepsMutators, bp2buildMutatorList)
 }
 
 // Register the pipeline of singletons, module types, and mutators for

android/testing.go

@@ -158,12 +158,17 @@ func (ctx *TestContext) FinalDepsMutators(f RegisterMutatorFunc) {
 	ctx.finalDeps = append(ctx.finalDeps, f)
 }
 
+func (ctx *TestContext) RegisterBp2BuildConfig(config Bp2BuildConfig) {
+	ctx.config.bp2buildPackageConfig = config
+}
+
 // RegisterBp2BuildMutator registers a BazelTargetModule mutator for converting a module
 // type to the equivalent Bazel target.
 func (ctx *TestContext) RegisterBp2BuildMutator(moduleType string, m func(TopDownMutatorContext)) {
 	f := func(ctx RegisterMutatorsContext) {
 		ctx.TopDown(moduleType, m)
 	}
+	ctx.config.bp2buildModuleTypeConfig[moduleType] = true
 	ctx.bp2buildMutators = append(ctx.bp2buildMutators, f)
 }
 

bp2build/bp2build.go

@@ -18,44 +18,48 @@ import (
 	"android/soong/android"
 	"fmt"
 	"os"
+	"strings"
 )
 
-// The Bazel bp2build code generator is responsible for writing .bzl files that are equivalent to
+// Codegen is the backend of bp2build. The code generator is responsible for
-// Android.bp files that are capable of being built with Bazel.
+// writing .bzl files that are equivalent to Android.bp files that are capable
+// of being built with Bazel.
 func Codegen(ctx *CodegenContext) CodegenMetrics {
 	outputDir := android.PathForOutput(ctx, "bp2build")
 	android.RemoveAllOutputDir(outputDir)
 
-	ruleShims := CreateRuleShims(android.ModuleTypeFactories())
-
 	buildToTargets, metrics := GenerateBazelTargets(ctx)
 
-	filesToWrite := CreateBazelFiles(ruleShims, buildToTargets, ctx.mode)
+	filesToWrite := CreateBazelFiles(nil, buildToTargets, ctx.mode)
+
+	generatedBuildFiles := []string{}
 	for _, f := range filesToWrite {
-		if err := writeFile(outputDir, ctx, f); err != nil {
+		p := getOrCreateOutputDir(outputDir, ctx, f.Dir).Join(ctx, f.Basename)
+		if err := writeFile(ctx, p, f.Contents); err != nil {
 			fmt.Errorf("Failed to write %q (dir %q) due to %q", f.Basename, f.Dir, err)
 		}
+		// if these generated files are modified, regenerate on next run.
+		generatedBuildFiles = append(generatedBuildFiles, p.String())
 	}
 
+	// The MANIFEST file contains the full list of files generated by bp2build, excluding itself.
+	// Its purpose is for downstream tools to understand the set of files converted by bp2build.
+	manifestFile := outputDir.Join(ctx, "MANIFEST")
+	writeFile(ctx, manifestFile, strings.Join(generatedBuildFiles, "\n"))
+	generatedBuildFiles = append(generatedBuildFiles, manifestFile.String())
+
 	return metrics
 }
 
-func writeFile(outputDir android.OutputPath, ctx android.PathContext, f BazelFile) error {
+// Get the output directory and create it if it doesn't exist.
-	return writeReadOnlyFile(ctx, getOutputPath(outputDir, ctx, f.Dir), f.Basename, f.Contents)
+func getOrCreateOutputDir(outputDir android.OutputPath, ctx android.PathContext, dir string) android.OutputPath {
+	dirPath := outputDir.Join(ctx, dir)
+	android.CreateOutputDirIfNonexistent(dirPath, os.ModePerm)
+	return dirPath
 }
 
-func getOutputPath(outputDir android.OutputPath, ctx android.PathContext, dir string) android.OutputPath {
+func writeFile(ctx android.PathContext, pathToFile android.OutputPath, content string) error {
-	return outputDir.Join(ctx, dir)
+	// These files are made editable to allow users to modify and iterate on them
-}
+	// in the source tree.
-
+	return android.WriteFileToOutputDir(pathToFile, []byte(content), 0644)
-// The auto-conversion directory should be read-only, sufficient for bazel query. The files
-// are not intended to be edited by end users.
-func writeReadOnlyFile(ctx android.PathContext, dir android.OutputPath, baseName, content string) error {
-	android.CreateOutputDirIfNonexistent(dir, os.ModePerm)
-	pathToFile := dir.Join(ctx, baseName)
-
-	// 0444 is read-only
-	err := android.WriteFileToOutputDir(pathToFile, []byte(content), 0444)
-
-	return err
 }

bp2build/build_conversion_test.go

@@ -412,7 +412,7 @@ load("//build/bazel/rules:rules.bzl", "my_library")`,
 		config := android.TestConfig(buildDir, nil, testCase.bp, nil)
 		ctx := android.NewTestContext(config)
 		ctx.RegisterModuleType("custom", customModuleFactory)
-		ctx.RegisterBp2BuildMutator("custom_starlark", customBp2BuildMutatorFromStarlark)
+		ctx.RegisterBp2BuildMutator("custom", customBp2BuildMutatorFromStarlark)
 		ctx.RegisterForBazelConversion()
 
 		_, errs := ctx.ParseFileList(dir, []string{"Android.bp"})
@@ -1144,7 +1144,7 @@ genrule {
 	}
 }
 
-func TestAllowlistingBp2buildTargets(t *testing.T) {
+func TestAllowlistingBp2buildTargetsExplicitly(t *testing.T) {
 	testCases := []struct {
 		moduleTypeUnderTest                string
 		moduleTypeUnderTestFactory         android.ModuleFactory
@@ -1222,6 +1222,124 @@ func TestAllowlistingBp2buildTargets(t *testing.T) {
 	}
 }
 
+func TestAllowlistingBp2buildTargetsWithConfig(t *testing.T) {
+	testCases := []struct {
+		moduleTypeUnderTest                string
+		moduleTypeUnderTestFactory         android.ModuleFactory
+		moduleTypeUnderTestBp2BuildMutator bp2buildMutator
+		expectedCount                      map[string]int
+		description                        string
+		bp2buildConfig                     android.Bp2BuildConfig
+		checkDir                           string
+		fs                                 map[string]string
+	}{
+		{
+			description:                        "test bp2build config package and subpackages config",
+			moduleTypeUnderTest:                "filegroup",
+			moduleTypeUnderTestFactory:         android.FileGroupFactory,
+			moduleTypeUnderTestBp2BuildMutator: android.FilegroupBp2Build,
+			expectedCount: map[string]int{
+				"migrated":                           1,
+				"migrated/but_not_really":            0,
+				"migrated/but_not_really/but_really": 1,
+				"not_migrated":                       0,
+				"also_not_migrated":                  0,
+			},
+			bp2buildConfig: android.Bp2BuildConfig{
+				"migrated":                android.Bp2BuildDefaultTrueRecursively,
+				"migrated/but_not_really": android.Bp2BuildDefaultFalse,
+				"not_migrated":            android.Bp2BuildDefaultFalse,
+			},
+			fs: map[string]string{
+				"migrated/Android.bp":                           `filegroup { name: "a" }`,
+				"migrated/but_not_really/Android.bp":            `filegroup { name: "b" }`,
+				"migrated/but_not_really/but_really/Android.bp": `filegroup { name: "c" }`,
+				"not_migrated/Android.bp":                       `filegroup { name: "d" }`,
+				"also_not_migrated/Android.bp":                  `filegroup { name: "e" }`,
+			},
+		},
+		{
+			description:                        "test bp2build config opt-in and opt-out",
+			moduleTypeUnderTest:                "filegroup",
+			moduleTypeUnderTestFactory:         android.FileGroupFactory,
+			moduleTypeUnderTestBp2BuildMutator: android.FilegroupBp2Build,
+			expectedCount: map[string]int{
+				"package-opt-in":             2,
+				"package-opt-in/subpackage":  0,
+				"package-opt-out":            1,
+				"package-opt-out/subpackage": 0,
+			},
+			bp2buildConfig: android.Bp2BuildConfig{
+				"package-opt-in":  android.Bp2BuildDefaultFalse,
+				"package-opt-out": android.Bp2BuildDefaultTrueRecursively,
+			},
+			fs: map[string]string{
+				"package-opt-in/Android.bp": `
+filegroup { name: "opt-in-a" }
+filegroup { name: "opt-in-b", bazel_module: { bp2build_available: true } }
+filegroup { name: "opt-in-c", bazel_module: { bp2build_available: true } }
+`,
+
+				"package-opt-in/subpackage/Android.bp": `
+filegroup { name: "opt-in-d" } // parent package not configured to DefaultTrueRecursively
+`,
+
+				"package-opt-out/Android.bp": `
+filegroup { name: "opt-out-a" }
+filegroup { name: "opt-out-b", bazel_module: { bp2build_available: false } }
+filegroup { name: "opt-out-c", bazel_module: { bp2build_available: false } }
+`,
+
+				"package-opt-out/subpackage/Android.bp": `
+filegroup { name: "opt-out-g", bazel_module: { bp2build_available: false } }
+filegroup { name: "opt-out-h", bazel_module: { bp2build_available: false } }
+`,
+			},
+		},
+	}
+
+	dir := "."
+	for _, testCase := range testCases {
+		fs := make(map[string][]byte)
+		toParse := []string{
+			"Android.bp",
+		}
+		for f, content := range testCase.fs {
+			if strings.HasSuffix(f, "Android.bp") {
+				toParse = append(toParse, f)
+			}
+			fs[f] = []byte(content)
+		}
+		config := android.TestConfig(buildDir, nil, "", fs)
+		ctx := android.NewTestContext(config)
+		ctx.RegisterModuleType(testCase.moduleTypeUnderTest, testCase.moduleTypeUnderTestFactory)
+		ctx.RegisterBp2BuildMutator(testCase.moduleTypeUnderTest, testCase.moduleTypeUnderTestBp2BuildMutator)
+		ctx.RegisterBp2BuildConfig(testCase.bp2buildConfig)
+		ctx.RegisterForBazelConversion()
+
+		_, errs := ctx.ParseFileList(dir, toParse)
+		android.FailIfErrored(t, errs)
+		_, errs = ctx.ResolveDependencies(config)
+		android.FailIfErrored(t, errs)
+
+		codegenCtx := NewCodegenContext(config, *ctx.Context, Bp2Build)
+
+		// For each directory, test that the expected number of generated targets is correct.
+		for dir, expectedCount := range testCase.expectedCount {
+			bazelTargets := generateBazelTargetsForDir(codegenCtx, dir)
+			if actualCount := len(bazelTargets); actualCount != expectedCount {
+				t.Fatalf(
+					"%s: Expected %d bazel target for %s package, got %d",
+					testCase.description,
+					expectedCount,
+					dir,
+					actualCount)
+			}
+
+		}
+	}
+}
+
 func TestCombineBuildFilesBp2buildTargets(t *testing.T) {
 	testCases := []struct {
 		description                        string

bp2build/conversion.go

@@ -21,14 +21,15 @@ func CreateBazelFiles(
 	mode CodegenMode) []BazelFile {
 	files := make([]BazelFile, 0, len(ruleShims)+len(buildToTargets)+numAdditionalFiles)
 
-	// Write top level files: WORKSPACE and BUILD. These files are empty.
+	// Write top level files: WORKSPACE. These files are empty.
 	files = append(files, newFile("", "WORKSPACE", ""))
+
+	if mode == QueryView {
 		// Used to denote that the top level directory is a package.
 		files = append(files, newFile("", GeneratedBuildFileName, ""))
 
 		files = append(files, newFile(bazelRulesSubDir, GeneratedBuildFileName, ""))
 
-	if mode == QueryView {
 		// These files are only used for queryview.
 		files = append(files, newFile(bazelRulesSubDir, "providers.bzl", providersBzl))
 

bp2build/conversion_test.go

@@ -87,18 +87,10 @@ func TestCreateBazelFiles_QueryView_AddsTopLevelFiles(t *testing.T) {
 func TestCreateBazelFiles_Bp2Build_AddsTopLevelFiles(t *testing.T) {
 	files := CreateBazelFiles(map[string]RuleShim{}, map[string]BazelTargets{}, Bp2Build)
 	expectedFilePaths := []filepath{
-		{
-			dir:      "",
-			basename: "BUILD",
-		},
 		{
 			dir:      "",
 			basename: "WORKSPACE",
 		},
-		{
-			dir:      bazelRulesSubDir,
-			basename: "BUILD",
-		},
 	}
 
 	assertFilecountsAreEqual(t, files, expectedFilePaths)

bp2build/testing.go

@@ -126,7 +126,7 @@ func (m *customBazelModule) GenerateAndroidBuildActions(ctx android.ModuleContex
 
 func customBp2BuildMutator(ctx android.TopDownMutatorContext) {
 	if m, ok := ctx.Module().(*customModule); ok {
-		if !m.ConvertWithBp2build() {
+		if !m.ConvertWithBp2build(ctx) {
 			return
 		}
 
@@ -147,7 +147,7 @@ func customBp2BuildMutator(ctx android.TopDownMutatorContext) {
 // module to target.
 func customBp2BuildMutatorFromStarlark(ctx android.TopDownMutatorContext) {
 	if m, ok := ctx.Module().(*customModule); ok {
-		if !m.ConvertWithBp2build() {
+		if !m.ConvertWithBp2build(ctx) {
 			return
 		}
 

cc/library_headers.go

@@ -86,7 +86,7 @@ func CcLibraryHeadersBp2Build(ctx android.TopDownMutatorContext) {
 		return
 	}
 
-	if !module.ConvertWithBp2build() {
+	if !module.ConvertWithBp2build(ctx) {
 		return
 	}
 

cc/object.go

@@ -131,7 +131,7 @@ func BazelObjectFactory() android.Module {
 // Bazel equivalent target, plus any necessary include deps for the cc_object.
 func ObjectBp2Build(ctx android.TopDownMutatorContext) {
 	m, ok := ctx.Module().(*Module)
-	if !ok || !m.ConvertWithBp2build() {
+	if !ok || !m.ConvertWithBp2build(ctx) {
 		return
 	}
 

cmd/soong_build/main.go

@@ -22,6 +22,7 @@ import (
 	"strings"
 
 	"android/soong/shared"
+
 	"github.com/google/blueprint/bootstrap"
 
 	"android/soong/android"

genrule/genrule.go

@@ -820,7 +820,7 @@ func BazelGenruleFactory() android.Module {
 
 func GenruleBp2Build(ctx android.TopDownMutatorContext) {
 	m, ok := ctx.Module().(*Module)
-	if !ok || !m.ConvertWithBp2build() {
+	if !ok || !m.ConvertWithBp2build(ctx) {
 		return
 	}
 

python/binary.go

@@ -61,7 +61,7 @@ func (m *bazelPythonBinary) GenerateAndroidBuildActions(ctx android.ModuleContex
 
 func PythonBinaryBp2Build(ctx android.TopDownMutatorContext) {
 	m, ok := ctx.Module().(*Module)
-	if !ok || !m.ConvertWithBp2build() {
+	if !ok || !m.ConvertWithBp2build(ctx) {
 		return
 	}
 

sh/sh_binary.go

@@ -521,7 +521,7 @@ func BazelShBinaryFactory() android.Module {
 
 func ShBinaryBp2Build(ctx android.TopDownMutatorContext) {
 	m, ok := ctx.Module().(*ShBinary)
-	if !ok || !m.ConvertWithBp2build() {
+	if !ok || !m.ConvertWithBp2build(ctx) {
 		return
 	}