pfw-macro-testing

MacroTesting

IMPORTANT

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Goal

Snapshot test your Swift macros using the MacroTesting library.

Quick start

1. Add the swift-macro-testing package dependency from 0.1.0 or newer.
2. Add the MacroTesting product to your test target's dependencies.
3. import MacroTesting as needed

API interface

Full API interface for when solution can't be found elsewhere: references/interface/MacroTesting.swiftinterface

How to write a macro test

Step 1: Create a new test target

Macro tests must be in their own target that only import the macro plugin and MacroTesting.

.testTarget(
  name: "CustomDumpMacrosTests",
  dependencies: [
    "CustomDumpMacros",
    .product(name: "MacroTesting", package: "swift-macro-testing"),
  ]
),

Step 2: Create a test suite

#if os(macOS)
  import MacroTesting
  import Testing

  @Suite(
    .macros(
      [MyMacro.self],
      record: .failed
    )
  )
  struct MyMacroTests {
    @Test func basics() {
      assertMacro {
        """
        @MyMacro struct Foo {
        }
        """
      }
    }
  }
#endif

Important: The inline snapshots are automatically generated by the test suite. ALWAYS wrap macro test files in #if os(macOS) (macro tests don't run on other platforms) NEVER write the trailing expansion yourself (it is generated by running the tests) ALWAYS delete existing inline snapshot when making edits to an assertion so that they can be regenerated by the tests

Step 3: Run tests

Running tests should generate the snapshots for you.