zeveisenberg/closeenough

Tag your floating-point or floating-point-ish values with `@CloseEnough`, and then compare them with a given precision when using `XCTAssertEqual` on their parent structs. This is useful because, while `XCTAssertEqual` provides [a variant](https://developer.apple.com/documentatio

Usage

To enable fuzzy comparison of your properties in tests, annotate them with the @CloseEnough property wrapper:

Declaration

struct Outer: Equatable {
  @CloseEnough
  var foo: Double

  @CloseEnough
  var bar: Date

  var inner: Inner // it works for nested structs too!
}

struct Inner: Equatable {
    @CloseEnough
    var baz
}

Test Code

You must provide a precision value for each type that is present in the structs (including nested structs) that you are comparing. Failure to do so will produce a test failure telling you which type(s) you forgot to express a precision for. If you want to compare with no fuzziness, supply a precision of 0 (or the additive identity for your type).

// Tests
withPrecisions([
  Double.self: 0.0001,
  Date.self: TimeInterval(10), // When comparing dates, difference is expressed as a time interval
]) {
  XCTAssertEqual(
    someValue,
    Outer(
      foo: 1.5,
      bar: Date(timeIntervalSinceReferenceDate: 1234),
      inner: Inner(
        baz: 11
      )
    )
  )
}

Custom Types

If you have a type that would benefit from close-enough comparison, conform it to the EquatableWithPrecision protocol and implement the required method, isApproximatelyEqual(to:precision:). Then, you can use the @CloseEnough property wrapper in your own code!

Package Metadata

Repository: zeveisenberg/closeenough

Default branch: main

README: README.md