Create test for invalid interests

tests/test_interestCalculator.c

@@ -46,5 +46,40 @@ void test_initiateInterest(void) {
     }
 }
 
+void test_initiateInterestFalse(void) {
 
-#endif // TEST
+   /* Arrange */
+
+    int length   = 10;
+    float startAmount[] = {34, 233, 4400, 1600, 245, 34544, 3767.32, 1422, 5435, 8199};
+    float yearlyInterest=12;
+    float durationInYears=2.5;
+
+    float monthlyInterest=8;
+    float durationInMonths=3.9;
+
+    float resultsYearly[length];
+    float resultsMonthly[length];
+    
+    float expectedYearly[]={0,0,0,0,0,0,0,0,0,0};
+    float expectedMonthly[]={0,0,0,0,0,0,0,0,0,0};
+
+   /* Act */
+
+    for (int i = 0; i < length; i++) {
+        resultsYearly[i]=initiateInterest(startAmount[i],yearlyInterest/100, durationInYears);
+    }
+    for (int i = 0; i < length; i++) {
+        resultsMonthly[i]=initiateInterest(startAmount[i],monthlyInterest/100, durationInMonths);
+    }
+
+   /* Assert*/
+
+    for (int i = 0; i < length; i++) {
+        TEST_ASSERT_FALSE(expectedYearly[i] == resultsYearly[i]);
+        TEST_ASSERT_FALSE(expectedMonthly[i] == resultsMonthly[i]);
+    }
+}
+
+
+#endif // TEST