Add support for excluding libraries from class loader contexts

A number of tests in the cts/tests/signature/api-check check for the
accessibility of classes from the android.test.base,
android.test.runner and android.test.mock libraries. Some tests expect
to find the classes other do not. Unfortunately, the tests use
libraries, specifically compatibility-device-util-axt, that depend on
the android.test... libraries which causes Soong to implicitly add
<uses-library> entries to the manifest so that they will be accessible
at runtime. That causes the tests that do not expect to find the
classes to fail.

Bug: 209607558
Test: m nothing
Change-Id: I54c194ab23d5a70df790ece3fe98f2b3d6a1c1f6

dexpreopt/class_loader_context_test.go

@@ -284,6 +284,111 @@ func TestCLCSdkVersionOrder(t *testing.T) {
 	})
 }
 
+func TestCLCMExcludeLibs(t *testing.T) {
+	ctx := testContext()
+	const optional = false
+	const implicit = true
+
+	excludeLibs := func(t *testing.T, m ClassLoaderContextMap, excluded_libs ...string) ClassLoaderContextMap {
+		// Dump the CLCM before creating a new copy that excludes a specific set of libraries.
+		before := m.Dump()
+
+		// Create a new CLCM that excludes some libraries.
+		c := m.ExcludeLibs(excluded_libs)
+
+		// Make sure that the original CLCM was not changed.
+		after := m.Dump()
+		android.AssertStringEquals(t, "input CLCM modified", before, after)
+
+		return c
+	}
+
+	t.Run("exclude nothing", func(t *testing.T) {
+		m := make(ClassLoaderContextMap)
+		m.AddContext(ctx, 28, "a", optional, implicit, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
+
+		a := excludeLibs(t, m)
+
+		android.AssertStringEquals(t, "output CLCM ", `{
+  "28": [
+    {
+      "Name": "a",
+      "Optional": false,
+      "Implicit": true,
+      "Host": "out/soong/a.jar",
+      "Device": "/system/a.jar",
+      "Subcontexts": []
+    }
+  ]
+}`, a.Dump())
+	})
+
+	t.Run("one item from list", func(t *testing.T) {
+		m := make(ClassLoaderContextMap)
+		m.AddContext(ctx, 28, "a", optional, implicit, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
+		m.AddContext(ctx, 28, "b", optional, implicit, buildPath(ctx, "b"), installPath(ctx, "b"), nil)
+
+		a := excludeLibs(t, m, "a")
+
+		expected := `{
+  "28": [
+    {
+      "Name": "b",
+      "Optional": false,
+      "Implicit": true,
+      "Host": "out/soong/b.jar",
+      "Device": "/system/b.jar",
+      "Subcontexts": []
+    }
+  ]
+}`
+		android.AssertStringEquals(t, "output CLCM ", expected, a.Dump())
+	})
+
+	t.Run("all items from a list", func(t *testing.T) {
+		m := make(ClassLoaderContextMap)
+		m.AddContext(ctx, 28, "a", optional, implicit, buildPath(ctx, "a"), installPath(ctx, "a"), nil)
+		m.AddContext(ctx, 28, "b", optional, implicit, buildPath(ctx, "b"), installPath(ctx, "b"), nil)
+
+		a := excludeLibs(t, m, "a", "b")
+
+		android.AssertStringEquals(t, "output CLCM ", `{}`, a.Dump())
+	})
+
+	t.Run("items from a subcontext", func(t *testing.T) {
+		s := make(ClassLoaderContextMap)
+		s.AddContext(ctx, AnySdkVersion, "b", optional, implicit, buildPath(ctx, "b"), installPath(ctx, "b"), nil)
+		s.AddContext(ctx, AnySdkVersion, "c", optional, implicit, buildPath(ctx, "c"), installPath(ctx, "c"), nil)
+
+		m := make(ClassLoaderContextMap)
+		m.AddContext(ctx, 28, "a", optional, implicit, buildPath(ctx, "a"), installPath(ctx, "a"), s)
+
+		a := excludeLibs(t, m, "b")
+
+		android.AssertStringEquals(t, "output CLCM ", `{
+  "28": [
+    {
+      "Name": "a",
+      "Optional": false,
+      "Implicit": true,
+      "Host": "out/soong/a.jar",
+      "Device": "/system/a.jar",
+      "Subcontexts": [
+        {
+          "Name": "c",
+          "Optional": false,
+          "Implicit": true,
+          "Host": "out/soong/c.jar",
+          "Device": "/system/c.jar",
+          "Subcontexts": []
+        }
+      ]
+    }
+  ]
+}`, a.Dump())
+	})
+}
+
 func checkError(t *testing.T, have error, want string) {
 	if have == nil {
 		t.Errorf("\nwant error: '%s'\nhave: none", want)