Create basic reentrant ClasspathFetcher targetprep

This will take over the responsibilities of StrictJavaPackagesTest's
setup code, and by fetching and processing all classpath data, as
defined in go/stricter-java-packages-test .

Test: atest ClasspathFetcherTest
Bug: 254647172
Change-Id: I93d2651994f7602d60ae91ca2401b83ae8c57baf

javatests/com/android/modules/targetprep/ClasspathFetcherTest.java

@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2022  The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.modules.targetprep;
+
+import static com.android.modules.targetprep.ClasspathFetcher.DEVICE_JAR_ARTIFACTS_TAG;
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertThrows;
+import static org.junit.Assert.fail;
+import static org.junit.Assume.assumeTrue;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+
+import com.android.tradefed.build.IDeviceBuildInfo;
+import com.android.tradefed.device.ITestDevice;
+import com.android.tradefed.invoker.IInvocationContext;
+import com.android.tradefed.invoker.InvocationContext;
+import com.android.tradefed.invoker.TestInformation;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.RuleChain;
+import org.junit.rules.TemporaryFolder;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+import org.mockito.Mock;
+import org.mockito.Mockito;
+import org.mockito.MockitoAnnotations;
+
+@RunWith(JUnit4.class)
+public class ClasspathFetcherTest {
+
+    private static final String SERIAL = "SERIAL";
+
+    @Mock IDeviceBuildInfo mMockBuildInfo;
+    @Mock ITestDevice mMockTestDevice;
+
+    private TestInformation mTestInfo;
+
+    @Before
+    public void setUp() throws Exception {
+        MockitoAnnotations.initMocks(this);
+
+        when(mMockTestDevice.getSerialNumber()).thenReturn(SERIAL);
+        when(mMockTestDevice.getDeviceDescriptor()).thenReturn(null);
+        when(mMockTestDevice.isAppEnumerationSupported()).thenReturn(false);
+        IInvocationContext context = new InvocationContext();
+        context.addAllocatedDevice("device", mMockTestDevice);
+        context.addDeviceBuildInfo("device", mMockBuildInfo);
+        mTestInfo = TestInformation.newBuilder().setInvocationContext(context).build();
+    }
+
+    @Test
+    public void testSingleArtifactFetcher() throws Exception {
+        final ClasspathFetcher fetcher = new ClasspathFetcher();
+        fetcher.setUp(mTestInfo);
+        assertThat(mTestInfo.properties().containsKey(DEVICE_JAR_ARTIFACTS_TAG)).isTrue();
+        fetcher.tearDown(mTestInfo, null);
+        assertThat(mTestInfo.properties().containsKey(DEVICE_JAR_ARTIFACTS_TAG)).isFalse();
+    }
+
+    @Test
+    public void testMultipleArtifactFetchers() throws Exception {
+        final ClasspathFetcher fetcher1 = new ClasspathFetcher();
+        final ClasspathFetcher fetcher2 = new ClasspathFetcher();
+
+        fetcher1.setUp(mTestInfo);
+        fetcher2.setUp(mTestInfo);
+        assertThat(mTestInfo.properties().containsKey(DEVICE_JAR_ARTIFACTS_TAG)).isTrue();
+        fetcher2.tearDown(mTestInfo, null);
+        assertThat(mTestInfo.properties().containsKey(DEVICE_JAR_ARTIFACTS_TAG)).isTrue();
+        fetcher1.tearDown(mTestInfo, null);
+        assertThat(mTestInfo.properties().containsKey(DEVICE_JAR_ARTIFACTS_TAG)).isFalse();
+    }
+}