add the LOCAL_DISABLE_TEST_CONFIG variable

Introduce and set the variable LOCAL_DISABLE_TEST_CONFIG varaible to be
true for the `android_test_helper_app` type modules.

Bug: 188927912
Test: rum 'm module-name' (`android_test_helper_app` type module)
Test: TreeHugger
Change-Id: I5db1029f31d8afe1ca5e9fab95e39d751971058d
diff --git a/java/androidmk.go b/java/androidmk.go
index 0154544..04357e0 100644
--- a/java/androidmk.go
+++ b/java/androidmk.go
@@ -460,6 +460,8 @@
 	entries := &entriesList[0]
 	entries.ExtraEntries = append(entries.ExtraEntries, func(ctx android.AndroidMkExtraEntriesContext, entries *android.AndroidMkEntries) {
 		testSuiteComponent(entries, a.appTestHelperAppProperties.Test_suites)
+		// introduce a flag variable to control the generation of the .config file
+		entries.SetString("LOCAL_DISABLE_TEST_CONFIG", "true")
 	})
 
 	return entriesList
diff --git a/java/androidmk_test.go b/java/androidmk_test.go
index 5eaa77b..246c0eb 100644
--- a/java/androidmk_test.go
+++ b/java/androidmk_test.go
@@ -188,3 +188,21 @@
 
 	android.AssertStringPathsRelativeToTopEquals(t, "LOCAL_SOONG_DEX_JAR", result.Config, []string{expectedSoongDexJar}, actualSoongDexJar)
 }
+
+func TestAndroidTestHelperApp_LocalDisableTestConfig(t *testing.T) {
+	ctx, _ := testJava(t, `
+		android_test_helper_app {
+			name: "foo",
+			srcs: ["a.java"],
+		}
+	`)
+
+	mod := ctx.ModuleForTests("foo", "android_common").Module()
+	entries := android.AndroidMkEntriesForTest(t, ctx, mod)[0]
+
+	expected := []string{"true"}
+	actual := entries.EntryMap["LOCAL_DISABLE_TEST_CONFIG"]
+	if !reflect.DeepEqual(expected, actual) {
+		t.Errorf("Unexpected flag value - expected: %q, actual: %q", expected, actual)
+	}
+}