Add fake for InstanceIDWithSubtype.java, in order to re-use unit test

components/gcm_driver/instance_id/android/javatests/src/org/chromium/components/gcm_driver/instance_id/FakeInstanceIDWithSubtype.java

Index: components/gcm_driver/instance_id/android/javatests/src/org/chromium/components/gcm_driver/instance_id/FakeInstanceIDWithSubtype.java
diff --git a/components/gcm_driver/instance_id/android/javatests/src/org/chromium/components/gcm_driver/instance_id/FakeInstanceIDWithSubtype.java b/components/gcm_driver/instance_id/android/javatests/src/org/chromium/components/gcm_driver/instance_id/FakeInstanceIDWithSubtype.java
new file mode 100644
index 0000000000000000000000000000000000000000..ed87213307fa60cac5512b39859cc51f2213bb6a
--- /dev/null
+++ b/components/gcm_driver/instance_id/android/javatests/src/org/chromium/components/gcm_driver/instance_id/FakeInstanceIDWithSubtype.java
@@ -0,0 +1,121 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.components.gcm_driver.instance_id;
+
+import android.content.Context;
+import android.os.Bundle;
+import android.os.Looper;
+
+import com.google.android.gms.iid.InstanceID;
+
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+
+import java.io.IOException;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Random;
+
+/**
+ * Fake for InstanceIDWithSubtype.

[Peter Beverloo, 2016/04/15 00:00:17]

Please document how it's fake. Even "avoids hitting the network" would already
be very valuable.

[johnme, 2016/04/15 16:00:43]

Done.

+ */
+@JNINamespace("instance_id")
+public class FakeInstanceIDWithSubtype extends InstanceIDWithSubtype {
+    private String mId = null;
+    private long mCreationTime = 0;
+    private Map<String, String> mTokens = new HashMap<>();
+
+    /** Enable this in all InstanceID tests to use this fake instead of hitting the network/disk. */
+    @CalledByNative
+    public static void clearDataAndSetEnabled(boolean enable) {
+        synchronized (InstanceID.class) {
+            getInstanceIDsForTesting().clear();
+        }
+        if (enable) {
+            sFakeFactoryForTesting = new FakeFactory() {
+                @Override
+                public InstanceIDWithSubtype create(Context context, String subtype) {
+                    return new FakeInstanceIDWithSubtype(context, subtype);
+                }
+            };
+        } else {
+            sFakeFactoryForTesting = null;
+        }
+    }
+
+    public FakeInstanceIDWithSubtype(Context context, String subtype) {

[Peter Beverloo, 2016/04/15 00:00:17]

private?

[johnme, 2016/04/15 16:00:43]

Done.

+        super(context, subtype);
+    }
+
+    @Override
+    public String getId() {
+        if (mId == null) {
+            mCreationTime = System.currentTimeMillis();
+            mId = randomBase64(11 /* length */);
+        }
+        return mId;
+    }
+
+    @Override
+    public long getCreationTime() {
+        return mCreationTime;
+    }
+
+    @Override
+    public String getToken(String authorizedEntity, String scope) throws IOException {
+        return getToken(authorizedEntity, scope, null);
+    }
+
+    @Override
+    public String getToken(String authorizedEntity, String scope, Bundle extras)
+            throws IOException {
+        if (Looper.getMainLooper() == Looper.myLooper())
+            throw new IOException(InstanceID.ERROR_MAIN_THREAD);

[Peter Beverloo, 2016/04/15 00:00:17]

nit: even one-line if-statements must have curly braces in Java. Elsewhere too.

[johnme, 2016/04/15 16:00:43]

Done.

+        String key = getSubtype() + ',' + authorizedEntity + ',' + scope;
+        String token = mTokens.get(key);
+        if (token == null && !"true".equals(extras.getString("fakeOffline"))) {

[Peter Beverloo, 2016/04/15 00:00:17]

Let's please introduce more detailed functionality like this in the tests that
will actually use it. (Code search shows no results for "fakeOffline" so I
presume it will be part of a follow-up patch?)

[johnme, 2016/04/15 16:00:43]

Removed.

+            getId();
+            token = mId + ':' + randomBase64(140 /* length */);
+            mTokens.put(key, token);
+        }
+        return token;
+    }
+
+    @Override
+    public void deleteToken(String authorizedEntity, String scope) throws IOException {
+        if (Looper.getMainLooper() == Looper.myLooper())
+            throw new IOException(InstanceID.ERROR_MAIN_THREAD);
+        String key = getSubtype() + ',' + authorizedEntity + ',' + scope;
+        mTokens.remove(key);
+        // Calling deleteToken causes ID to be generated; can be observed though getCreationTime.
+        getId();
+    }
+
+    @Override
+    public void deleteInstanceID() throws IOException {
+        synchronized (InstanceID.class) {
+            getInstanceIDsForTesting().remove(getSubtype());
+            if (Looper.getMainLooper() == Looper.myLooper())
+                throw new IOException(InstanceID.ERROR_MAIN_THREAD);
+            mTokens.clear();
+            mCreationTime = 0;
+            mId = null;
+        }
+    }
+
+    private static final String BASE64URL_ALPHABET =
+            "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-_";

[Peter Beverloo, 2016/04/15 00:00:17]

nit: statics go at the top of the class

[johnme, 2016/04/15 16:00:43]

The style guide says "Define fields either at the top of the file or immediately
before the methods that use them."
http://source.android.com/source/code-style.html#define-fields-in-standard-pl....

In this case the latter seems clearly more readable. Though even better would be
to move it into the randomBase64 method, which I've done. Thanks to the string
constant pool it should be equally efficient.

+    /** Returns a random (not necessarily valid) base64url encoded string. */

[Peter Beverloo, 2016/04/15 00:00:17]

Please give this a proper doc block.

Also note that URL-safe base64 generated like this will always be decode-able,
because the trailing equal-sign padding is generally optional for that encoding.

[johnme, 2016/04/15 16:00:43]

Ah good - removed "not necessarily valid". This is a proper doc block though.
See
http://source.android.com/source/code-style.html#use-javadoc-standard-comments

+    private static String randomBase64(int length) {
+        Random random = new Random();
+        StringBuilder sb = new StringBuilder(length);
+        for (int i = 0; i < length; i++) {
+            int index = random.nextInt(BASE64URL_ALPHABET.length());
+            sb.append(BASE64URL_ALPHABET.charAt(index));
+        }
+        return sb.toString();
+    }
+}