separate unittest folder

unittests/mocks/PeriodicTaskIFMock.h

@@ -0,0 +1,25 @@
+#ifndef FSFW_UNITTEST_TESTS_MOCKS_PERIODICTASKMOCK_H_
+#define FSFW_UNITTEST_TESTS_MOCKS_PERIODICTASKMOCK_H_
+
+#include <fsfw/tasks/ExecutableObjectIF.h>
+#include <fsfw/tasks/PeriodicTaskBase.h>
+
+class PeriodicTaskMock : public PeriodicTaskBase {
+ public:
+  PeriodicTaskMock(TaskPeriod period, TaskDeadlineMissedFunction dlmFunc)
+      : PeriodicTaskBase(period, dlmFunc) {}
+
+  virtual ~PeriodicTaskMock() {}
+  /**
+   * @brief	With the startTask method, a created task can be started
+   *          for the first time.
+   */
+  virtual ReturnValue_t startTask() override {
+    initObjsAfterTaskCreation();
+    return HasReturnvaluesIF::RETURN_OK;
+  };
+
+  virtual ReturnValue_t sleepFor(uint32_t ms) override { return HasReturnvaluesIF::RETURN_OK; };
+};
+
+#endif  // FSFW_UNITTEST_TESTS_MOCKS_PERIODICTASKMOCK_H_