Create TestInputChannel and TestLooper to better test InputConsumerNoResampling

Created TestInputChannel and TestLooper to control how InputMessages are
batched in InputConsumerNoResampling_test

Bug: 297226446
Flag: EXEMPT refactor
Test: TEST=libinput_tests; m $TEST && $ANDROID_HOST_OUT/nativetest64/$TEST/$TEST --gtest_filter="InputConsumerTest*"
Change-Id: I036593b311a93ec301e8b9776b461505e853119f
diff --git a/libs/input/tests/TestInputChannel.h b/libs/input/tests/TestInputChannel.h
new file mode 100644
index 0000000..43253ec
--- /dev/null
+++ b/libs/input/tests/TestInputChannel.h
@@ -0,0 +1,66 @@
+/**
+ * Copyright 2024 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.
+ */
+
+#pragma once
+
+#include <queue>
+#include <string>
+
+#include <android-base/result.h>
+#include <gtest/gtest.h>
+#include <input/InputTransport.h>
+#include <utils/Errors.h>
+
+namespace android {
+
+class TestInputChannel final : public InputChannel {
+public:
+    explicit TestInputChannel(const std::string& name);
+
+    /**
+     * Enqueues a message in mReceivedMessages.
+     */
+    void enqueueMessage(const InputMessage& message);
+
+    /**
+     * Pushes message to mSentMessages. In the default implementation, InputChannel sends messages
+     * through a file descriptor. TestInputChannel, on the contrary, stores sent messages in
+     * mSentMessages for assertion reasons.
+     */
+    status_t sendMessage(const InputMessage* message) override;
+
+    /**
+     * Returns an InputMessage from mReceivedMessages. This is done instead of retrieving data
+     * directly from fd.
+     */
+    base::Result<InputMessage> receiveMessage() override;
+
+    /**
+     * Returns if mReceivedMessages is not empty.
+     */
+    bool probablyHasInput() const override;
+
+    void assertFinishMessage(uint32_t seq, bool handled);
+
+    void assertNoSentMessages() const;
+
+private:
+    // InputMessages received by the endpoint.
+    std::queue<InputMessage> mReceivedMessages;
+    // InputMessages sent by the endpoint.
+    std::queue<InputMessage> mSentMessages;
+};
+} // namespace android