Testing

Why This Matters

Testing is built into Arden CLI, so correctness checks stay in the same workflow as build and run. For beginners: you mark functions with @Test and run arden test.

Minimal Test

@Test
function sampleTest(): None {
    assert_eq(1, 1);
    return None;
}

Run Tests

arden test

Single file:

arden test --path examples/single_file/tooling_and_ffi/24_test_attributes/24_test_attributes.arden

List tests without running:

arden test --list --path examples/single_file/tooling_and_ffi/24_test_attributes/24_test_attributes.arden

Filter by substring:

arden test --filter Addition --path examples/single_file/tooling_and_ffi/24_test_attributes/24_test_attributes.arden

Test Attributes

@Test: marks a test
@Ignore: skips a test (optional reason)
@Before: runs before each test
@After: runs after each test
@BeforeAll: runs once before suite
@AfterAll: runs once after suite

Signature Rules (Compiler-Enforced)

@Test, @Before, @After, @BeforeAll, @AfterAll functions must be:

non-extern
non-async
parameterless
non-generic
return type None

@Ignore requires @Test on the same function. @Test cannot be combined with lifecycle attributes. Each suite allows at most one @BeforeAll and one @AfterAll.

@Ignore with reason example:

@Test
@Ignore("waiting for fixture update")
function notReadyYet(): None {
    return None;
}

Execution Order

@BeforeAll
per non-ignored test: @Before -> test -> @After
@AfterAll

Practical Guidance

keep tests deterministic and independent
test one behavior per test where possible
use --list to verify discovery before long runs
use --filter for fast local iteration on one failure
use fail("why this is invalid") when a branch should be unreachable in a test

Common Mistakes

hidden shared mutable state between tests
assertions that depend on timing/random/environment
relying only on happy-path tests
tagging async/extern/parameterized function as @Test
using @Ignore on non-@Test function

Attributes
Example: 24_test_attributes