diff --git a/bp2build/testing.go b/bp2build/testing.go
index 4e63d19..c059add 100644
--- a/bp2build/testing.go
+++ b/bp2build/testing.go
@@ -91,65 +91,66 @@
 
 func RunBp2BuildTestCase(t *testing.T, registerModuleTypes func(ctx android.RegistrationContext), tc Bp2buildTestCase) {
 	t.Helper()
-	bp2buildSetup := func(ctx *android.TestContext) {
-		registerModuleTypes(ctx)
-		ctx.RegisterForBazelConversion()
-	}
+	bp2buildSetup := android.GroupFixturePreparers(
+		android.FixtureRegisterWithContext(registerModuleTypes),
+		SetBp2BuildTestRunner,
+	)
 	runBp2BuildTestCaseWithSetup(t, bp2buildSetup, tc)
 }
 
 func RunApiBp2BuildTestCase(t *testing.T, registerModuleTypes func(ctx android.RegistrationContext), tc Bp2buildTestCase) {
 	t.Helper()
-	apiBp2BuildSetup := func(ctx *android.TestContext) {
-		registerModuleTypes(ctx)
-		ctx.RegisterForApiBazelConversion()
-	}
+	apiBp2BuildSetup := android.GroupFixturePreparers(
+		android.FixtureRegisterWithContext(registerModuleTypes),
+		SetApiBp2BuildTestRunner,
+	)
 	runBp2BuildTestCaseWithSetup(t, apiBp2BuildSetup, tc)
 }
 
-func runBp2BuildTestCaseWithSetup(t *testing.T, setup func(ctx *android.TestContext), tc Bp2buildTestCase) {
+func runBp2BuildTestCaseWithSetup(t *testing.T, extraPreparer android.FixturePreparer, tc Bp2buildTestCase) {
 	t.Helper()
 	dir := "."
 	filesystem := make(map[string][]byte)
-	toParse := []string{
-		"Android.bp",
-	}
 	for f, content := range tc.Filesystem {
-		if strings.HasSuffix(f, "Android.bp") {
-			toParse = append(toParse, f)
-		}
 		filesystem[f] = []byte(content)
 	}
-	config := android.TestConfig(buildDir, nil, tc.Blueprint, filesystem)
-	ctx := android.NewTestContext(config)
 
-	setup(ctx)
-	ctx.RegisterModuleType(tc.ModuleTypeUnderTest, tc.ModuleTypeUnderTestFactory)
-
-	// A default configuration for tests to not have to specify bp2build_available on top level targets.
-	bp2buildConfig := android.NewBp2BuildAllowlist().SetDefaultConfig(
-		allowlists.Bp2BuildConfig{
-			android.Bp2BuildTopLevel: allowlists.Bp2BuildDefaultTrueRecursively,
-		},
-	)
-	for _, f := range tc.KeepBuildFileForDirs {
-		bp2buildConfig.SetKeepExistingBuildFile(map[string]bool{
-			f: /*recursive=*/ false,
-		})
-	}
-	ctx.RegisterBp2BuildConfig(bp2buildConfig)
-
-	_, parseErrs := ctx.ParseFileList(dir, toParse)
-	if errored(t, tc, parseErrs) {
-		return
-	}
-	_, resolveDepsErrs := ctx.ResolveDependencies(config)
-	if errored(t, tc, resolveDepsErrs) {
-		return
+	preparers := []android.FixturePreparer{
+		extraPreparer,
+		android.FixtureMergeMockFs(filesystem),
+		android.FixtureWithRootAndroidBp(tc.Blueprint),
+		android.FixtureRegisterWithContext(func(ctx android.RegistrationContext) {
+			ctx.RegisterModuleType(tc.ModuleTypeUnderTest, tc.ModuleTypeUnderTestFactory)
+		}),
+		android.FixtureModifyContext(func(ctx *android.TestContext) {
+			// A default configuration for tests to not have to specify bp2build_available on top level
+			// targets.
+			bp2buildConfig := android.NewBp2BuildAllowlist().SetDefaultConfig(
+				allowlists.Bp2BuildConfig{
+					android.Bp2BuildTopLevel: allowlists.Bp2BuildDefaultTrueRecursively,
+				},
+			)
+			for _, f := range tc.KeepBuildFileForDirs {
+				bp2buildConfig.SetKeepExistingBuildFile(map[string]bool{
+					f: /*recursive=*/ false,
+				})
+			}
+			ctx.RegisterBp2BuildConfig(bp2buildConfig)
+		}),
+		android.FixtureModifyEnv(func(env map[string]string) {
+			if tc.UnconvertedDepsMode == errorModulesUnconvertedDeps {
+				env["BP2BUILD_ERROR_UNCONVERTED"] = "true"
+			}
+		}),
 	}
 
-	parseAndResolveErrs := append(parseErrs, resolveDepsErrs...)
-	if tc.ExpectedErr != nil && checkError(t, parseAndResolveErrs, tc.ExpectedErr) {
+	preparer := android.GroupFixturePreparers(preparers...)
+	if tc.ExpectedErr != nil {
+		pattern := "\\Q" + tc.ExpectedErr.Error() + "\\E"
+		preparer = preparer.ExtendWithErrorHandler(android.FixtureExpectsOneErrorPattern(pattern))
+	}
+	result := preparer.RunTestWithCustomResult(t).(*BazelTestResult)
+	if len(result.Errs) > 0 {
 		return
 	}
 
@@ -157,27 +158,115 @@
 	if tc.Dir != "" {
 		checkDir = tc.Dir
 	}
-	codegenCtx := NewCodegenContext(config, ctx.Context, Bp2Build)
-	codegenCtx.unconvertedDepMode = tc.UnconvertedDepsMode
-	bazelTargets, errs := generateBazelTargetsForDir(codegenCtx, checkDir)
-	if tc.ExpectedErr != nil {
-		if checkError(t, errs, tc.ExpectedErr) {
-			return
-		} else {
-			t.Errorf("Expected error: %q, got: %q and %q", tc.ExpectedErr, errs, parseAndResolveErrs)
-		}
-	} else {
-		android.FailIfErrored(t, errs)
+	expectedTargets := map[string][]string{
+		checkDir: tc.ExpectedBazelTargets,
 	}
-	if actualCount, expectedCount := len(bazelTargets), len(tc.ExpectedBazelTargets); actualCount != expectedCount {
+
+	result.CompareAllBazelTargets(t, tc.Description, expectedTargets, true)
+}
+
+// SetBp2BuildTestRunner customizes the test fixture mechanism to run tests in Bp2Build mode.
+var SetBp2BuildTestRunner = android.FixtureSetTestRunner(&bazelTestRunner{Bp2Build})
+
+// SetApiBp2BuildTestRunner customizes the test fixture mechanism to run tests in ApiBp2build mode.
+var SetApiBp2BuildTestRunner = android.FixtureSetTestRunner(&bazelTestRunner{ApiBp2build})
+
+// bazelTestRunner customizes the test fixture mechanism to run tests of the bp2build and
+// apiBp2build build modes.
+type bazelTestRunner struct {
+	mode CodegenMode
+}
+
+func (b *bazelTestRunner) FinalPreparer(result *android.TestResult) android.CustomTestResult {
+	ctx := result.TestContext
+	switch b.mode {
+	case Bp2Build:
+		ctx.RegisterForBazelConversion()
+	case ApiBp2build:
+		ctx.RegisterForApiBazelConversion()
+	default:
+		panic(fmt.Errorf("unknown build mode: %d", b.mode))
+	}
+
+	return &BazelTestResult{TestResult: result}
+}
+
+func (b *bazelTestRunner) PostParseProcessor(result android.CustomTestResult) {
+	bazelResult := result.(*BazelTestResult)
+	ctx := bazelResult.TestContext
+	config := bazelResult.Config
+	_, errs := ctx.ResolveDependencies(config)
+	if bazelResult.CollateErrs(errs) {
+		return
+	}
+
+	codegenCtx := NewCodegenContext(config, ctx.Context, Bp2Build)
+	res, errs := GenerateBazelTargets(codegenCtx, false)
+	if bazelResult.CollateErrs(errs) {
+		return
+	}
+
+	// Store additional data for access by tests.
+	bazelResult.conversionResults = res
+}
+
+// BazelTestResult is a wrapper around android.TestResult to provide type safe access to the bazel
+// specific data stored by the bazelTestRunner.
+type BazelTestResult struct {
+	*android.TestResult
+
+	// The result returned by the GenerateBazelTargets function.
+	conversionResults
+}
+
+// CompareAllBazelTargets compares the BazelTargets produced by the test for all the directories
+// with the supplied set of expected targets.
+//
+// If ignoreUnexpected=false then this enforces an exact match where every BazelTarget produced must
+// have a corresponding expected BazelTarget.
+//
+// If ignoreUnexpected=true then it will ignore directories for which there are no expected targets.
+func (b BazelTestResult) CompareAllBazelTargets(t *testing.T, description string, expectedTargets map[string][]string, ignoreUnexpected bool) {
+	actualTargets := b.buildFileToTargets
+
+	// Generate the sorted set of directories to check.
+	dirsToCheck := android.SortedStringKeys(expectedTargets)
+	if !ignoreUnexpected {
+		// This needs to perform an exact match so add the directories in which targets were
+		// produced to the list of directories to check.
+		dirsToCheck = append(dirsToCheck, android.SortedStringKeys(actualTargets)...)
+		dirsToCheck = android.SortedUniqueStrings(dirsToCheck)
+	}
+
+	for _, dir := range dirsToCheck {
+		expected := expectedTargets[dir]
+		actual := actualTargets[dir]
+
+		if expected == nil {
+			if actual != nil {
+				t.Errorf("did not expect any bazel modules in %q but found %d", dir, len(actual))
+			}
+		} else if actual == nil {
+			expectedCount := len(expected)
+			if expectedCount > 0 {
+				t.Errorf("expected %d bazel modules in %q but did not find any", expectedCount, dir)
+			}
+		} else {
+			b.CompareBazelTargets(t, description, expected, actual)
+		}
+	}
+}
+
+func (b BazelTestResult) CompareBazelTargets(t *testing.T, description string, expectedContents []string, actualTargets BazelTargets) {
+	if actualCount, expectedCount := len(actualTargets), len(expectedContents); actualCount != expectedCount {
 		t.Errorf("%s: Expected %d bazel target (%s), got %d (%s)",
-			tc.Description, expectedCount, tc.ExpectedBazelTargets, actualCount, bazelTargets)
+			description, expectedCount, expectedContents, actualCount, actualTargets)
 	} else {
-		for i, target := range bazelTargets {
-			if w, g := tc.ExpectedBazelTargets[i], target.content; w != g {
+		for i, actualTarget := range actualTargets {
+			if w, g := expectedContents[i], actualTarget.content; w != g {
 				t.Errorf(
-					"%s: Expected generated Bazel target to be `%s`, got `%s`",
-					tc.Description, w, g)
+					"%s[%d]: Expected generated Bazel target to be `%s`, got `%s`",
+					description, i, w, g)
 			}
 		}
 	}