Add java.RegisterRequiredBuildComponentsForTest function

Insulate tests that exercise code in the java package from having to
register the build components provided by the java package by providing
a single function that registers them all. This follows the pattern
currently used in the cc and rust packages.

This change is in preparation for switching the dex_bootjars singleton
from a singleton, which does not require a module definition in order
to be instantiated, to a singleton module which does. That will require
adding a module definition into java.GatherRequiredDepsForTest() and
this change ensures that the required components will have been
registered in every test.

Bug: 177892522
Test: m nothing
Change-Id: I6475db8240894947dd07c89a940a3e4f201aa598

java/testing.go

@@ -95,6 +95,29 @@ func prebuiltApisFilesForLibs(apiLevels []string, sdkLibs []string) map[string][
 	return fs
 }
 
+// Register build components provided by this package that are needed by tests.
+//
+// In particular this must register all the components that are used in the `Android.bp` snippet
+// returned by GatherRequiredDepsForTest()
+func RegisterRequiredBuildComponentsForTest(ctx android.RegistrationContext) {
+	RegisterAARBuildComponents(ctx)
+	RegisterAppBuildComponents(ctx)
+	RegisterAppImportBuildComponents(ctx)
+	RegisterAppSetBuildComponents(ctx)
+	RegisterDexpreoptBootJarsComponents(ctx)
+	RegisterDocsBuildComponents(ctx)
+	RegisterGenRuleBuildComponents(ctx)
+	RegisterJavaBuildComponents(ctx)
+	RegisterPrebuiltApisBuildComponents(ctx)
+	RegisterRuntimeResourceOverlayBuildComponents(ctx)
+	RegisterSdkLibraryBuildComponents(ctx)
+	RegisterStubsBuildComponents(ctx)
+	RegisterSystemModulesBuildComponents(ctx)
+}
+
+// Gather the module definitions needed by tests that depend upon code from this package.
+//
+// Returns an `Android.bp` snippet that defines the modules that are needed by this package.
 func GatherRequiredDepsForTest() string {
 	var bp string