Macro assertify::assertify

macro_rules! assertify {
    #[proc_macro_hack] => { ... };
}

Assert an expression is true or give a useful error when it isn’t.

If the expression contains a comparison, e.g. ==, then the failure message will display the value of both sides of the comparison. Note that the right side will be listed as the “expected” value — think “right” as in “correct.”

Examples

Error for a failed comparison

assertify!(1 + 2 == 0);

Produces:

---- tests::fail_simple_eq stdout ----
thread 'tests::simple_eq' panicked at 'failed: 1 + 2 == 0
  actual:      3
  expected: == 0
', src/lib.rs:96:9

Error for other failures

assertify!(false);

Produces:

---- tests::fail_simple_literal stdout ----
thread 'tests::fail_simple_literal' panicked at 'failed: false', src/lib.rs:131:9