assert - w3toppers.com

How do you assert that a certain exception is thrown in JUnit tests?

It depends on the JUnit version and what assert libraries you use. For JUnit5 and 4.13 see answer https://stackoverflow.com/a/2935935/2986984 If you use assertJ or google-truth, see answer https://stackoverflow.com/a/41019785/2986984 The original answer for JUnit <= 4.12 was: @Test(expected = IndexOutOfBoundsException.class) public void testIndexOutOfBoundsException() { ArrayList emptyList = new ArrayList(); Object o = emptyList.get(0); } Though answer … Read more

What does the “assert” keyword do? [duplicate]

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

When should assertions stay in production code? [closed]

Assertions are comments that do not become outdated. They document which theoretical states are intended, and which states should not occur. If code is changed so states allowed change, the developer is soon informed and needs to update the assertion.

Design by contract using assertions or exceptions? [closed]

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

How to do a JUnit assert on a message in a logger

I’ve needed this several times as well. I’ve put together a small sample below, which you’d want to adjust to your needs. Basically, you create your own Appender and add it to the logger you want. If you’d want to collect everything, the root logger is a good place to start, but you can use … Read more

Best practice for using assert?

Asserts should be used to test conditions that should never happen. The purpose is to crash early in the case of a corrupt program state. Exceptions should be used for errors that can conceivably happen, and you should almost always create your own Exception classes. For example, if you’re writing a function to read from … Read more

Static assert in C

C11 standard adds the _Static_assert keyword. This is implemented since gcc-4.6: _Static_assert (0, “assert1”); /* { dg-error “static assertion failed: \”assert1\”” } */ The first slot needs to be an integral constant expression. The second slot is a constant string literal which can be long (_Static_assert(0, L”assertion of doom!”)). I should note that this is … Read more

What is the use of “assert” in Python?

The assert statement exists in almost every programming language. It has two main uses: It helps detect problems early in your program, where the cause is clear, rather than later when some other operation fails. A type error in Python, for example, can go through several layers of code before actually raising an Exception if … Read more

How do you assert that a certain exception is thrown in JUnit 4 tests?

How to automatically generate a stacktrace when my program crashes

For Linux and I believe Mac OS X, if you’re using gcc, or any compiler that uses glibc, you can use the backtrace() functions in execinfo.h to print a stacktrace and exit gracefully when you get a segmentation fault. Documentation can be found in the libc manual. Here’s an example program that installs a SIGSEGV … Read more