Add test for currency change to GBP

tests/test_currencyExchange.c

@@ -39,5 +39,34 @@ void test_toUSD(void) {
 
 }
 
+void test_toGBP(void) {
+
+    /* Arrange */
+
+    int length   = 5;
+    float euro[] = {34, 233, 400, 100, 45};
+    
+    float expectedGBP[length];
+    float resultGBP[length];
+
+    for (int i = 0; i < length; i++) {
+        resultGBP[i] = toGBP(euro[i]);
+    }
+
+    /* Act */
+
+    for (int i = 0; i < length; i++) {
+        expectedGBP[i] = euro[i] * CURRENT_GBP_RATE_OF_ONE_EURO;
+    }
+
+    /* Assert */
+
+    for (int i = 0; i < length; i++) {
+        TEST_ASSERT_EQUAL_FLOAT(expectedGBP[i], resultGBP[i]);
+    }
+
+}
+
+
 
 #endif // TEST