added test for determining binary string length

test/conversionOfNumbers/test_conversionOfNumbers.c

@@ -14,4 +14,16 @@ void test_convert2ToBinaryStr(){
 
     //assert
     TEST_ASSERT_EQUAL_STRING(expected, result);
+}
+
+void test_binaryStringLengthOfInput5is3(){
+    //arrange
+    int result;
+    int expected = 3;
+
+    //act
+    result = binaryStrLen(5);
+
+    //assert
+    TEST_ASSERT_EQUAL_INT(expected, result);
 }