Expected value followed by the actual value

When comparing values with assertions, it is customary for the expected (correct) value to be given first, followed by the actual value:

    Assert.AreEqual( <expectedValue>, <actualValue> ); 

While it makes no difference to the true or false nature of equality, it can make a difference to messages when tests fail with some testing frameworks (for example, "got 2 but expected 3" has a very different meaning to "got 3 but expected 2"). Hence, the following assertion would output a message that would be confusing, since 2 was our expected result:

    public void TestTwoEqualsThreeShouldFail() {
         // Arrange
         int expectedResult = 2;
 
         // Act
         int result = 1 + 2; // 3 !!!
 
         // Assert
         Assert.AreEqual(result, expectedResult);
     } 

The following screenshot illustrates how we will get a misleading message when the arguments are the wrong way around in our assertion method...