Add AppSearchSessionUnitTest to cover platform scenarios.

This change adds test for verify Exception propagation.

Test: presubmit
Bug: 162450968
Bug: 175067650
Change-Id: I211860a3e6215eb8da962de351486f9fb5b770af
diff --git a/core/tests/coretests/src/android/app/appsearch/AppSearchSessionUnitTest.java b/core/tests/coretests/src/android/app/appsearch/AppSearchSessionUnitTest.java
new file mode 100644
index 0000000..fe31b90
--- /dev/null
+++ b/core/tests/coretests/src/android/app/appsearch/AppSearchSessionUnitTest.java
@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2021 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 android.app.appsearch;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import static org.testng.Assert.expectThrows;
+
+import android.content.Context;
+
+import androidx.test.core.app.ApplicationProvider;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.Objects;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.Executor;
+
+public class AppSearchSessionUnitTest {
+    private final Context mContext = ApplicationProvider.getApplicationContext();
+    private final AppSearchManager mAppSearch = mContext.getSystemService(AppSearchManager.class);
+    private final Executor mExecutor = mContext.getMainExecutor();
+    private AppSearchSession mSearchSession;
+
+    @Before
+    public void setUp() throws Exception {
+        // Remove all documents from any instances that may have been created in the tests.
+        Objects.requireNonNull(mAppSearch);
+        AppSearchManager.SearchContext searchContext = new AppSearchManager.SearchContext.Builder()
+                .setDatabaseName("testDb").build();
+        CompletableFuture<AppSearchResult<AppSearchSession>> future = new CompletableFuture<>();
+        mAppSearch.createSearchSession(searchContext, mExecutor, future::complete);
+        mSearchSession = future.get().getResultValue();
+
+        CompletableFuture<AppSearchResult<SetSchemaResponse>> schemaFuture =
+                new CompletableFuture<>();
+        mSearchSession.setSchema(
+                new SetSchemaRequest.Builder().setForceOverride(true).build(), mExecutor,
+                schemaFuture::complete);
+
+        schemaFuture.get().getResultValue();
+    }
+
+    @Test
+    public void testPutDocument_throwsNullException() throws Exception {
+        // Create a document
+        AppSearchEmail inEmail =
+                new AppSearchEmail.Builder("uri1")
+                        .setFrom("from@example.com")
+                        .setTo("to1@example.com", "to2@example.com")
+                        .setSubject("testPut example")
+                        .setBody("This is the body of the testPut email")
+                        .build();
+
+        // clear the document bundle to make our service crash and throw an NullPointerException.
+        inEmail.getBundle().clear();
+        CompletableFuture<AppSearchBatchResult<String, Void>> putDocumentsFuture =
+                new CompletableFuture<>();
+
+        // Index the broken document.
+        mSearchSession.put(
+                new PutDocumentsRequest.Builder().addGenericDocuments(inEmail).build(),
+                mExecutor, new BatchResultCallback<String, Void>() {
+                    @Override
+                    public void onResult(AppSearchBatchResult<String, Void> result) {
+                        putDocumentsFuture.complete(result);
+                    }
+
+                    @Override
+                    public void onSystemError(Throwable throwable) {
+                        putDocumentsFuture.completeExceptionally(throwable);
+                    }
+                });
+
+        // Verify the NullPointException has been thrown.
+        ExecutionException executionException = expectThrows(ExecutionException.class,
+                putDocumentsFuture::get);
+        assertThat(executionException.getCause()).isInstanceOf(NullPointerException.class);
+    }
+}