added test for converting negative integer

test/conversionOfNumbers/test_conversionOfNumbers.c

@@ -62,4 +62,16 @@ void test_binaryStringLengthOfInputNegative10is5(){
 
     //assert
     TEST_ASSERT_EQUAL_INT(expected, result);
+}
+
+void test_convertNegative12ToBinaryStrNegative1100(){
+    //arrange
+    char* result;
+    char expected[] = "-1100";
+
+    //act
+    result = convertIntToBinaryStr(-12);
+
+    //assert
+    TEST_ASSERT_EQUAL_STRING(expected, result);
 }