Unit Testing (@Test)

Implementation status: @Test discovery and execution Implemented; JUnit-shaped hooks (@TestSetup / @TestTeardown / @TestBefore / @TestAfter) Implemented; recursive tests/**/*.sy and single-file syx test path/to/file.sy Implemented; import Testing + assert / assertEq Implemented (explicit import, not auto-injected); @Test async plus await that can complete inside the body (via the syx test JSON pass) Implemented. For a file without @Test, if the entry calls test(name:fn:), those closures run before that entry finishes, and the JSON case name is {file}.{name}. Not implemented: Testing auto-import.

syx test compiles the test files into the VM and runs the cases carrying @Test; a failure exits non-zero. For a product example see examples/test_demo.sy; for CLI details see docs/9_UsageGuide.md; for the narrow charter and follow-up slices see plan/topics/syx-test.md.

Minimal Working Example

import Testing

@Test
func adds() {
    assertEq(1 + 1, 2)
    assert(true)
}

Put the file under the project's tests/ directory (nesting is allowed), then:

syx test .

Discovery Rules

Input	Behavior
syx test . (or the project root)	Collects tests/**/*.sy recursively; case names include the relative path (e.g. nested/math.add)
syx test path/to/file.sy	Runs only the @Tests in that file
--filter substr	Filters by case-name substring; non-matches are recorded as skipped
--format human|json|tap|junit	Report format (default human)

Each test file is compiled and run independently.

Hooks (PascalCase)

Attribute	Timing
@TestSetup	Once before all cases in the file
@TestBefore	Before each @Test
@Test	The case itself
@TestAfter	After each @Test
@TestTeardown	Once after all cases in the file

import Logging
import Testing

@TestSetup
func boot() {
    Log.info("once before all")
}

@TestBefore
func prep() {
    Log.info("before each")
}

@Test
func first() {
    assertEq(1 + 1, 2)
}

@TestAfter
func clean() {
    Log.info("after each")
}

@TestTeardown
func done() {
    Log.info("once after all")
}

import Testing

packages/testing/mod.sy provides:

API	Purpose
assert(condition: Bool)	If the condition is false → the case fails (Host Err, not a process panic)
assertEq(actual: Sendable, expected: Sendable)	If the values are unequal → failure (value_equals); R-12 (≠ Object). test(name:fn:) takes fn: Function.

You must write import Testing; syx test does not auto-inject the module. When there is no @Test, the closures registered by test(name:fn:) run and appear in the JSON ({file}.{name}). A file with @Test does not open additional sibling cases; if a registered closure fails, the failure text is merged into that @Test. expectEqual is still not a discovery path. @Test async func … may await inside its body (same drain shape as async func main); an explicit import Testing is still required. Not implemented: auto-import.

Relationship to main

A test file usually does not need func main(): the driver discovers by attribute and calls the hooks and cases. A normal syx run entry still requires main; do not mix the two narratives in the same file.

Honest Boundaries

• In the Host capability matrix, TestingAssert / TestingAssertEq are partial, VM real only (the syx test product path); no claim of mir/llvm/wasm GA.
• ≠ auto-import, ≠ all HostFns with status=implemented, ≠ a complete async test matrix.