Testing

Testing

Tests live next to the code they test, Go-style: files named *_test.sl hold functions named test_*, taking nothing and returning nothing, which fail through assert or panic.

// calc_test.sl
fn test_add() {
    assert(add(2, 3) == 5);
}

fn test_clamp() {
    let got = clamp(15, 0, 10);       // private functions are reachable:
    assert(got == 10, "got " + to_str(got));   // tests are in the package
}

slangc test                 # the package in the current directory
slangc test path/to/pkg     # another one
slangc test --run clamp     # only tests whose name contains "clamp"

ok   test_add (52us)
FAIL test_clamp (30us)
     got 15 at calc.test_clamp:7
FAIL: 1 of 2 failed (190us)

• Each test runs in its own task, so a failing test is reported with its message and location and the run carries on. Tests run one at a time, so output stays in order.
• *_test.sl files never reach a normal build. Test helpers can't leak into a program, and a test file's imports can't add link flags to one.
• Programs are testable too. When the package is a program rather than a library, slangc test does not run its top-level statements: the test runner is main. Functions, structs and methods are all there.
• Exit status is 0 when every test passes, 1 when any fails, and 2 when the tests cannot be run (a test_ function with parameters, say). A package with no test files exits 0 and says so.
• --keep keeps the generated runner and prints where it is.