Debugging and Tests

Whim has language constructs for checks and debug output.

assert!

assert!($condition) requires a boolean. It throws AssertionError when the value is false.

$answer = 6 * 7;
assert!($answer == 42);

The error shows the source expression. A comparison also shows its left and right values.

Assertions always run. Whim has no release mode that removes them.

debug!

debug!($value) prints the call site and a detailed form of the value.

$numbers = vec[1, 2, 3];
debug!($numbers);

Strings show their byte length and escaped bytes. Objects show their class, generic arguments, visible property values, and hidden private values. Arrays show their size and items.

Debug output stops after 64 collection items and 32 nested levels. This keeps a large or cyclic value from filling the terminal. The path is relative to the working directory when possible.

Do not parse debug output. Its form may change between Whim releases.

Writing tests

Use assert! for each condition:

assert!(2 + 2 == 4);
assert!(length!('whim') == 4);
assert!(Whim\Str\contains('whim', 'him'));
assert!(contains_key!(vec[1, 2], 1));

You may add a message after the condition:

$status = 200;
assert!($status == 200, 'the request must succeed');

Whim does not impose a test file layout or test runner. A test is a normal Whim program that throws on failure. A shell, build tool, or Whim script can run a set of such files.

Stack traces

An uncaught throwable prints its type, message, source, and call stack. Normal traces stop at TraceBoundary frames. Set WHIM_FULL_TRACE=true when debugging the standard library itself:

WHIM_FULL_TRACE=true whim tests/example.whim

Parameters marked SensitiveParameter remain hidden in either trace mode.

panic!('message') prints the same kind of stack trace, then exits with status 255. It takes a literal string and cannot be caught. Use it to mark a state that must never occur.

Bytecode

Use disassembly when a result differs between optimized and unoptimized code, or when checking whether the optimizer found a known type:

whim disassemble example.whim > optimized.txt
WHIM_OPTIMIZATIONS=off whim disassemble example.whim > plain.txt

Bytecode is an implementation detail. It may change in any release.