The answer from Kent Beck, co-creator of JUnit (where possibly this convention originates, since his earlier SUnit doesn’t appear to have included assertEquals): Line a bunch of assertEquals in a row. Having expected first makes them read better. In the initial version of my answer, I said that I didn’t understand this. Here’s what I … Read more
The rule of thumb is that you should use assertions when you are trying to catch your own errors, and exceptions when trying to catch other people’s errors. In other words, you should use exceptions to check the preconditions for the public API functions, and whenever you get any data that are external to your … Read more
The last assert would have given you a warning (SyntaxWarning: assertion is always true, perhaps remove parentheses?) if you ran it through a full interpreter, not through IDLE. Because assert is a keyword and not a function, you are actually passing in a tuple as the first argument and leaving off the second argument. Recall … Read more
If you launch your program with -enableassertions (or -ea for short) then this statement assert cond; is equivalent to if (!cond) throw new AssertionError(); If you launch your program without this option, the assert statement will have no effect. For example, assert d >= 0 && d <= s.length();, as posted in your question, is … Read more
Static assert is used to make assertions at compile time. When the static assertion fails, the program simply doesn’t compile. This is useful in different situations, like, for example, if you implement some functionality by code that critically depends on unsigned int object having exactly 32 bits. You can put a static assert like this … Read more
For “Visual Studio Team Test” it appears you apply the ExpectedException attribute to the test’s method. Sample from the documentation here: A Unit Testing Walkthrough with Visual Studio Team Test [TestMethod] [ExpectedException(typeof(ArgumentException), “A userId of null was inappropriately allowed.”)] public void NullUserIdInConstructor() { LogonInfo logonInfo = new LogonInfo(null, “P@ss0word”); }
A hack I’ve seen around is to use the && operator. Since a pointer “is true” if it’s non-null, you can do the following without altering the condition: assert(a == b && “A is not equal to B”); Since assert shows the condition that failed, it will display your message too. If it’s not enough, … Read more
You can use IsNull.nullValue() method: import static org.hamcrest.Matchers.is; import static org.hamcrest.Matchers.nullValue; assertThat(attr.getValue(), is(nullValue()));
The main difference is: ExpectedException() attribute makes test passed if exception occurs in any place in the test method. The usage of Assert.Throws() allows to specify exact place of the code where exception is expected. NUnit 3.0 drops official support for ExpectedException altogether. So, I definitely prefer to use Assert.Throws() method rather than ExpectedException() attribute.
In a debug compilation, Assert takes in a Boolean condition as a parameter, and shows the error dialog if the condition is false. The program proceeds without any interruption if the condition is true. If you compile in Release, all Debug.Assert‘s are automatically left out.