Unit tests: Add stubs for analogin_api.c functions

Currently there are no stub implementations of the analogin_api.c
functions. As we increase unit testing coverage, these will be required.

Author: hazzlim

hal/tests/UNITTESTS/doubles/CMakeLists.txt

@@ -17,13 +17,15 @@ target_compile_definitions(mbed-stubs-hal
         DEVICE_PWMOUT
         DEVICE_WATCHDOG
         MBED_WDOG_ASSERT=1
+        DEVICE_ANALOGIN
 )
 
 target_sources(mbed-stubs-hal
     PRIVATE
         pwmout_api_stub.c
         us_ticker_stub.cpp
         watchdog_api_stub.c
+        analogin_api_stub.c
 )
 
 target_link_libraries(mbed-stubs-hal

hal/tests/UNITTESTS/doubles/analogin_api_stub.c

@@ -0,0 +1,49 @@
+/*
+ * Copyright (c) 2021 Arm Limited and affiliates.
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * 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.
+ */
+#include "hal/analogin_api.h"
+#include <stddef.h>
+
+#if DEVICE_ANALOGIN
+
+void analogin_init_direct(analogin_t *obj, const PinMap *pinmap)
+{
+}
+
+void analogin_init(analogin_t *obj, PinName pin)
+{
+}
+
+void analogin_free(analogin_t *obj)
+{
+}
+
+float analogin_read(analogin_t *obj)
+{
+    return 0;
+}
+
+uint16_t analogin_read_u16(analogin_t *obj)
+{
+    return 0;
+}
+
+const PinMap *analogin_pinmap(void)
+{
+    return NULL;
+}
+
+#endif // DEVICE_ANALOGIN