Testowanie i debugowanie makr

Dlaczego testować makra?

// The swift-syntax package ships SwiftSyntaxMacrosTestSupport
// with assertMacroExpansion for testing macro output

assertMacroExpansion

import SwiftSyntaxMacrosTestSupport
import XCTest

final class StringifyMacroTests: XCTestCase {
  func testStringify() throws {
    assertMacroExpansion(
      "#stringify(1 + 2)",
      expandedSource: "(1 + 2, \"1 + 2\")",
      macros: ["stringify": StringifyMacro.self]
    )
  }
}

Testowanie makr dołączanych

assertMacroExpansion(
  "@AddID struct User { var name: String }",
  expandedSource: """
  struct User {
    var name: String
    var id = UUID()
  }
  """,
  macros: ["AddID": AddIDMacro.self]
)

Testowanie generowania diagnostyki

assertMacroExpansion(
  "@AddID class Foo {}",
  expandedSource: "class Foo {}",
  diagnostics: [
    DiagnosticSpec(message: "@AddID can only be applied to structs", line: 1, column: 1)
  ],
  macros: ["AddID": AddIDMacro.self]
)

Rozwijanie makr w Xcode

// Before expansion:
let (v, s) = #stringify(1 + 2)
// After:
let (v, s) = (1 + 2, "1 + 2")

Debugowanie makr za pomocą print

// In macro implementation:
print("[StringifyMacro] expanding: \(node.description)", to: &standardError)

Punkty przerwania w testach makr

// Set a breakpoint in StringifyMacro.expansion()
// Run the test target — breakpoints are hit

Inspekcja drzewa składniowego

print(node.debugDescription)
// Prints the full SyntaxTree hierarchy

Testowanie wielu wariantów argumentów

func testNoArgument() {
  assertMacroExpansion(
    "#stringify()",
    expandedSource: "#stringify()",
    diagnostics: [DiagnosticSpec(message: "Need an argument", line: 1, column: 1)],
    macros: ["stringify": StringifyMacro.self]
  )
}

Testy integracyjne

// In test app:
let (val, src) = #stringify(Date.now)
XCTAssertEqual(src, "Date.now")

CI dla testów makr

// CI command:
swift test --package-path MyMacros

Szybkie sprawdzenie

Podsumowanie lekcji