divkit/client/ios/DivKitTests/Expressions/FunctionTests.swift

@testable import DivKit

import XCTest

final class FunctionTests: XCTestCase {
  private let context = ExpressionContext(
    evaluators: { _ in nil },
    variableValueProvider: { _ in nil },
    customFunctionsStorageProvider: { _ in nil },
    errorTracker: { _ in }
  )

  private var unaryFunction = FunctionUnary<String, Bool> { _ in true }
  private var binaryFunction: SimpleFunction!

  private var lastArgs: [Any] = []

  override func setUp() {
    binaryFunction = FunctionBinary<Double, Double, Bool> { [unowned self] in
      lastArgs = [$0, $1]
      return true
    }
  }

  func test_invoke_FunctionBinary_WithoutCast() throws {
    _ = try binaryFunction.invoke([1.2, 3.4], context: context)

    checkLastArgs([1.2, 3.4])
  }

  func test_invoke_FunctionBinary_WithCast() throws {
    _ = try binaryFunction.invoke([2, 3.4], context: context)

    checkLastArgs([2.0, 3.4])
  }

  func test_invoke_FunctionBinary_WithInvalidArguments() throws {
    XCTAssertThrowsError(
      _ = try binaryFunction.invoke([1.2, true], context: context),
      ExpressionError("Invalid argument type: expected Number, got Boolean.")
    )
  }

  func test_invoke_FunctionBinary_WithWrongArgumentCount() throws {
    XCTAssertThrowsError(
      _ = try binaryFunction.invoke([1.2], context: context),
      ExpressionError("Exactly 2 argument(s) expected.")
    )
  }

  func test_invoke_FunctionUnary_WithInvalidArguments() throws {
    XCTAssertThrowsError(
      _ = try unaryFunction.invoke([1], context: context),
      ExpressionError("Invalid argument type: expected String, got Integer.")
    )
  }

  func test_invoke_FunctionUnary_WithWrongArgumentCount() throws {
    XCTAssertThrowsError(
      _ = try unaryFunction.invoke(["one", "two"], context: context),
      ExpressionError("Exactly 1 argument(s) expected.")
    )
  }

  func test_invoke_OverloadedFunction_WithoutCast() throws {
    var success = false

    let function = OverloadedFunction(
      functions: [
        FunctionBinary<Int, Int, Bool> { _, _ in
          XCTFail("Function must not be called")
          return true
        },
        FunctionBinary<Double, Double, Bool> { _, _ in
          success = true
          return true
        },
      ]
    )

    _ = try function.invoke([1.2, 3.4], context: context)

    XCTAssertTrue(success)
  }

  func test_invoke_OverloadedFunction_WithCast() throws {
    var success = false

    let function = OverloadedFunction(
      functions: [
        FunctionBinary<Int, Int, Bool> { _, _ in
          XCTFail("Function must not be called")
          return true
        },
        FunctionBinary<Double, Double, Bool> { _, _ in
          success = true
          return true
        },
      ]
    )

    _ = try function.invoke([2, 3.4], context: context)

    XCTAssertTrue(success)
  }

  func test_invoke_OverloadedFunction_WithInvalidArguments() throws {
    let function = OverloadedFunction(
      functions: [
        FunctionBinary<Int, Int, Bool> { _, _ in
          XCTFail("Function must not be called")
          return true
        },
        FunctionBinary<Double, Double, Bool> { _, _ in
          XCTFail("Function must not be called")
          return true
        },
      ]
    )

    XCTAssertThrowsError(try function.invoke([1.2, true], context: context)) {
      XCTAssertTrue($0 is NoMatchingSignatureError)
    }
  }

  func test_invoke_OverloadedFunction_WithCast_MultipleMatches() throws {
    let function = OverloadedFunction(
      functions: [
        FunctionBinary<Int, Double, Bool> { _, _ in true },
        FunctionBinary<Double, Int, Bool> { _, _ in true },
      ]
    )

    XCTAssertThrowsError(
      _ = try function.invoke([2, 3], context: context),
      ExpressionError("Multiple matching overloads")
    )
  }

  private func checkLastArgs(_ args: [AnyHashable]) {
    XCTAssertEqual(args, lastArgs as! [AnyHashable])
  }
}

extension ExpressionError: Equatable {
  public static func ==(lhs: ExpressionError, rhs: ExpressionError) -> Bool {
    lhs.description == rhs.description
  }
}