Increase test independence

If a test fails without unregistering an agent, other tests will
see their requests match the old agent. That means any test failing
will fail all subsequent tests, which is not very helpful.

Solve this by making sure the agents are unregistered before the
test ends. Also ensure the requests are unregistered.

Test: NetworkAgentTest
Bug: 139268426
Change-Id: If183d78298aa2a0bcae9e2487199dee14014cdfb
Merged-In: I2c167803d478d31fd85dc6e6e621f35d36c68fb4
(cherry-picked from aosp/1284556)

tests/cts/net/src/android/net/cts/NetworkAgentTest.kt

@@ -67,6 +67,9 @@ class NetworkAgentTest {
     private class Provider(context: Context, looper: Looper) :
             NetworkProvider(context, looper, "NetworkAgentTest NetworkProvider")
 
+    private val agentsToCleanUp = mutableListOf<NetworkAgent>()
+    private val callbacksToCleanUp = mutableListOf<TestableNetworkCallback>()
+
     @Before
     fun setUp() {
         instrumentation.getUiAutomation().adoptShellPermissionIdentity()
@@ -75,11 +78,13 @@ class NetworkAgentTest {
 
     @After
     fun tearDown() {
+        agentsToCleanUp.forEach { it.unregister() }
+        callbacksToCleanUp.forEach { mCM.unregisterNetworkCallback(it) }
         mHandlerThread.quitSafely()
         instrumentation.getUiAutomation().dropShellPermissionIdentity()
     }
 
-    internal class TestableNetworkAgent(
+    private class TestableNetworkAgent(
         looper: Looper,
         nc: NetworkCapabilities,
         lp: LinkProperties,
@@ -94,12 +99,10 @@ class NetworkAgentTest {
         }
 
         override fun onBandwidthUpdateRequested() {
-            super.onBandwidthUpdateRequested()
             history.add(OnBandwidthUpdateRequested)
         }
 
         override fun onNetworkUnwanted() {
-            super.onNetworkUnwanted()
             history.add(OnNetworkUnwanted)
         }
 
@@ -109,6 +112,11 @@ class NetworkAgentTest {
         }
     }
 
+    private fun requestNetwork(request: NetworkRequest, callback: TestableNetworkCallback) {
+        mCM.requestNetwork(request, callback)
+        callbacksToCleanUp.add(callback)
+    }
+
     private fun createNetworkAgent(): TestableNetworkAgent {
         val nc = NetworkCapabilities().apply {
             addTransportType(NetworkCapabilities.TRANSPORT_TEST)
@@ -120,7 +128,9 @@ class NetworkAgentTest {
         }
         val lp = LinkProperties()
         val config = NetworkAgentConfig.Builder().build()
-        return TestableNetworkAgent(mHandlerThread.looper, nc, lp, config)
+        return TestableNetworkAgent(mHandlerThread.looper, nc, lp, config).also {
+            agentsToCleanUp.add(it)
+        }
     }
 
     private fun createConnectedNetworkAgent(): Pair<TestableNetworkAgent, TestableNetworkCallback> {
@@ -129,8 +139,9 @@ class NetworkAgentTest {
                 .addTransportType(NetworkCapabilities.TRANSPORT_TEST)
                 .build()
         val callback = TestableNetworkCallback(timeoutMs = DEFAULT_TIMEOUT_MS)
-        mCM.requestNetwork(request, callback)
+        requestNetwork(request, callback)
-        val agent = createNetworkAgent().also { it.register() }
+        val agent = createNetworkAgent()
+        agent.register()
         agent.markConnected()
         return agent to callback
     }