Testing

Expect is the assertion library a test declaration uses. Every matcher throws TestFailure.assertion when it does not hold, so a test stops at its first failed assertion; a missing try is a compile error. maxon test runs a project’s tests — see CLI_REFERENCE.md.

test 'splits on commas'
  let parts = "a,b,c".split(",")
  try Expect.equal(parts.count(), expected: 3)
  try Expect.equal("a,b".replace(",", with: ";"), expected: "a;b")
  try Expect.close(0.1 + 0.2, expected: 0.3, within: 0.000001)
  try Expect.isTrue(parts.count() == 3, message: "three parts")
  try Expect.contains("haystack", needle: "st")
end 'splits on commas'

A failure prints a report to stderr at the assertion, naming the caller’s file and line:

FAIL split.test.maxon:20: Expect.equal
  expected: 5
  received: 4
  message: two plus two

The message: line appears only when a message was given.

Matchers

Every matcher also takes message String = "", file String = __file__ and line SourceLineNumber = __line__; only fail requires its message.

Matcher	Argument types	Holds when
Expect.equal(actual, expected:)	integer, String, bool	actual == expected
Expect.notEqual(actual, expected:)	integer, String, bool	actual != expected
Expect.greaterThan(actual, than:)	integer, float	actual > than
Expect.lessThan(actual, than:)	integer, float	actual < than
Expect.atLeast(actual, than:)	integer, float	actual >= than
Expect.atMost(actual, than:)	integer, float	actual <= than
Expect.close(actual, expected:, within:)	float	abs(actual - expected) <= within
Expect.isTrue(actual)	bool	actual is true
Expect.isFalse(actual)	bool	actual is false
Expect.contains(haystack, needle:)	String	haystack contains needle
Expect.startsWith(haystack, needle:)	String	prefix match
Expect.endsWith(haystack, needle:)	String	suffix match
Expect.isEmpty(haystack)	String	no characters
Expect.fail(message)	—	never; fails unconditionally

Each name is one overload set chosen by argument type, including through a method call (Expect.equal(parts.count(), expected: 3)) and through an enum’s name, ordinal and rawValue. String values are quoted in the report, so empty or space-padded values stay visible.

Floats have no equal: exact float equality can pass on one target and fail on another, so Expect.equal(1.5, expected: 1.5) does not compile. Use close(…, within:). NaN satisfies no comparison, so it fails every float matcher.

For any other Equatable and Stringable type, isTrue is the general form: try Expect.isTrue(a == b, message: "expected {b}, got {a}").

enum TestFailure implements Error
  assertion
end 'TestFailure'

A test declaration is implicitly throws TestFailure. An error of any other type that reaches the end of a test body is reported as a failure naming the error and the try that threw it.