Allow cc_test to build a test per source file

Some cc_test modules want a test per source file, for example when
there is global state that needs to be reset between each test
suite, but no way to reset it.  Allow them to specify test_per_src: true,
which will cause a separate test to be built for each source file.

Change-Id: I3dbf1202fb070437cb0109f195dc11a6440061ee

cc/cc.go

@@ -1192,6 +1192,12 @@ func (c *ccBinary) installModule(ctx common.AndroidModuleContext, flags ccFlags)
 
 type ccTest struct {
 	ccBinary
+
+	testProperties struct {
+		// test_per_src: Create a separate test for each source file.  Useful when there is
+		// global state that can not be torn down and reset between each test suite.
+		Test_per_src bool
+	}
 }
 
 var (
@@ -1234,7 +1240,23 @@ func (c *ccTest) installModule(ctx common.AndroidModuleContext, flags ccFlags) {
 func NewCCTest() (blueprint.Module, []interface{}) {
 	module := &ccTest{}
 	return newCCDynamic(&module.ccDynamic, module, common.HostAndDeviceSupported,
-		common.MultilibFirst, &module.binaryProperties)
+		common.MultilibFirst, &module.binaryProperties, &module.testProperties)
+}
+
+func TestPerSrcMutator(mctx blueprint.EarlyMutatorContext) {
+	if test, ok := mctx.Module().(*ccTest); ok {
+		if test.testProperties.Test_per_src {
+			testNames := make([]string, len(test.properties.Srcs))
+			for i, src := range test.properties.Srcs {
+				testNames[i] = strings.TrimSuffix(src, filepath.Ext(src))
+			}
+			tests := mctx.CreateLocalVariations(testNames...)
+			for i, src := range test.properties.Srcs {
+				tests[i].(*ccTest).properties.Srcs = []string{src}
+				tests[i].(*ccTest).binaryProperties.Stem = testNames[i]
+			}
+		}
+	}
 }
 
 //

cmd/soong_build/main.go

@@ -56,6 +56,7 @@ func main() {
 	// Mutators
 	ctx.RegisterEarlyMutator("arch", common.ArchMutator)
 	ctx.RegisterEarlyMutator("link", cc.LinkageMutator)
+	ctx.RegisterEarlyMutator("test_per_src", cc.TestPerSrcMutator)
 
 	// Singletons
 	ctx.RegisterSingletonType("checkbuild", common.CheckbuildSingleton)