Add downloads to the deletion helper.

This adds a deletion service to delete files in the Downloads
folder. All of the files there are collected and offered to the
user to delete.

Bug: 28621781
Change-Id: I94431f9abc3a0afa2d07dbab763312c09e830aef

tests/unit/src/com/android/settings/deletionhelper/FetchDownloadsLoaderTest.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright (C) 2016 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.settings.deletionhelper;
+
+import com.android.settings.deletionhelper.FetchDownloadsLoader.DownloadsResult;
+
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.rules.TemporaryFolder;
+import org.junit.runners.JUnit4;
+
+import java.io.File;
+import java.io.FileWriter;
+
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertEquals;
+
+@RunWith(JUnit4.class)
+public class FetchDownloadsLoaderTest {
+    @Rule
+    public TemporaryFolder temporaryFolder = new TemporaryFolder();
+
+    @Test
+    public void testEmptyDirectory() throws Exception {
+        DownloadsResult result =
+                FetchDownloadsLoader.collectFiles(temporaryFolder.getRoot());
+        assertNotNull(result);
+        assertEquals(0, result.totalSize);
+        assertEquals(0, result.files.size());
+    }
+
+    @Test
+    public void testFilesInDirectory() throws Exception {
+        temporaryFolder.newFile();
+        temporaryFolder.newFile();
+
+        DownloadsResult result =
+                FetchDownloadsLoader.collectFiles(temporaryFolder.getRoot());
+        assertNotNull(result);
+        assertEquals(0, result.totalSize);
+        assertEquals(2, result.files.size());
+    }
+
+    @Test
+    public void testNestedDirectories() throws Exception {
+        File tempDir = temporaryFolder.newFolder();
+
+        File testFile = File.createTempFile("test", null, tempDir);
+        testFile.deleteOnExit();
+        DownloadsResult result =
+                FetchDownloadsLoader.collectFiles(temporaryFolder.getRoot());
+        assertNotNull(result);
+        assertEquals(0, result.totalSize);
+        assertEquals(1, result.files.size());
+    }
+
+    @Test
+    public void testSumFileSizes() throws Exception {
+        File first = temporaryFolder.newFile();
+        FileWriter fileWriter = new FileWriter(first);
+        fileWriter.write("test");
+        fileWriter.close();
+
+        File second = temporaryFolder.newFile();
+        fileWriter = new FileWriter(second);
+        fileWriter.write("test2");
+        fileWriter.close();
+
+        DownloadsResult result =
+                FetchDownloadsLoader.collectFiles(temporaryFolder.getRoot());
+        assertNotNull(result);
+        assertEquals(9, result.totalSize);
+        assertEquals(2, result.files.size());
+    }
+}