Reference

Testing

Eta ships with a small testing library, std.test, and a dedicated runner binary, eta_test. Tests are ordinary Eta values: a test case is a name + thunk; a group is a name + a list of children.

Reference: stdlib integration tests live under stdlib/tests/.

Quick example

(module my-tests
  (import std.test std.io)
  (begin
    (define suite
      (make-group "arithmetic"
        (list
          (make-test "addition"
            (lambda () (assert-equal 4 (+ 2 2))))
          (make-test "near-equal"
            (lambda () (assert-approx-equal 0.1 (- 0.3 0.2) 1e-9))))))

    (define results (run suite))
    (print-summary (summary results))))

etai my-tests.eta

API surface

Constructors

Form	Builds
`(make-test name thunk)`	A leaf test
`(make-group name children)`	A group node

Groups may contain tests and other groups, building a tree.

Assertions

Assertion	Passes if
`(assert-true x)`	`x` is truthy
`(assert-false x)`	`x` is `#f`
`(assert-equal expected actual)`	`equal?`
`(assert-not-equal expected actual)`	`not equal?`
`(assert-approx-equal expected actual tol)`	Numeric within `tol`

A failed assertion raises a tagged exception that the runner records without aborting the suite.

Runner

Function	Returns
`(run group-or-test)`	A result tree
`(summary results)`	Aggregate `test-summary` record
`summary-total`, `summary-passed`, `summary-failed`	Counts

Output

Function	Format
`(print-summary s)`	Human-readable summary
`(print-tap results)`	TAP 13 to stdout
`(print-junit results)`	JUnit XML to stdout

The `eta_test` runner

eta_test is the dedicated test driver. It discovers test files, loads them, and produces machine-readable output for IDE integration.

eta_test path/to/tests           # run a directory tree
eta_test --tap   …               # TAP output
eta_test --junit out.xml …       # JUnit XML to file
eta_test --filter "regex"  …     # name filter

VS Code’s Test Explorer picks up eta_test --json … output through the extension — see VS Code extension.

CI integration

# GitHub Actions excerpt
- name: Run Eta tests
  run: eta_test --junit test-results.xml stdlib/tests
- uses: actions/upload-artifact@v5
  with:
    name: test-results
    path: test-results.xml