Added unittest for logarithmFunction

src/test/c/test_taschenrechner.c

@@ -132,4 +132,11 @@ void test_tangentFunction(void) {
     TEST_ASSERT_EQUAL_FLOAT(0.0, tangentFunction(0.0));
 }
 
+// Logarithm function
+void test_logarithmFunction(void) {
+    // Your test code here
+    TEST_ASSERT_EQUAL_FLOAT(1.0, logarithmFunction(10.0));
+}
+
+
 #endif // TEST