Failing to infer mocked type

[Pavel Ivashkov]

New Issue Checklist

• I updated my Mockingbird framework and CLI to the latest version
• I searched for existing GitHub issues

Description

Inferred return type of mock() is not usable.

Generator Bugs

$ mockingbird generate \
--only-protocols \
--disable-cache \
--targets 'Sample' \
--outputs "${SRCROOT}/MockingbirdMocks/SampleMocks.generated.swift"

1. A minimal example of the original source

protocol Bird {
  func fly()
}

2. The actual mocking code generated

//
//  SampleMocks.generated.swift
//  Sample
//
//  Generated by Mockingbird v0.11.0.
//  DO NOT EDIT
//

@testable import Mockingbird
@testable import Sample
import Foundation
import Swift

private var genericTypesStaticMocks = Mockingbird.Synchronized<[String: Mockingbird.StaticMock]>([:])

// MARK: - Mocked Bird

public final class BirdMock: Sample.Bird, Mockingbird.Mock, BirdAbstractMockType {
  static let staticMock = Mockingbird.StaticMock()
  public let mockingContext = Mockingbird.MockingContext()
  public let stubbingContext = Mockingbird.StubbingContext()
  public let mockMetadata = Mockingbird.MockMetadata(["generator_version": "0.11.0", "module_name": "Sample"])
  public var sourceLocation: Mockingbird.SourceLocation? {
    get { return stubbingContext.sourceLocation }
    set {
      stubbingContext.sourceLocation = newValue
      BirdMock.staticMock.stubbingContext.sourceLocation = newValue
    }
  }

  fileprivate init(sourceLocation: Mockingbird.SourceLocation) {
    Mockingbird.checkVersion(for: self)
    self.sourceLocation = sourceLocation
  }

  // MARK: Mocked `fly`()

  public func `fly`() -> Void {
    let invocation: Mockingbird.Invocation = Mockingbird.Invocation(selectorName: "`fly`() -> Void", arguments: [])
    mockingContext.didInvoke(invocation)
    let implementation = stubbingContext.implementation(for: invocation, optional: true)
    if let concreteImplementation = implementation as? () -> Void {
      concreteImplementation()
    } else {
      (implementation as? () -> Void)?()
    }
  }

  public func `fly`() -> Mockingbird.Mockable<Mockingbird.MethodDeclaration, () -> Void, Void> {
    let invocation: Mockingbird.Invocation = Mockingbird.Invocation(selectorName: "`fly`() -> Void", arguments: [])
    return Mockingbird.Mockable<Mockingbird.MethodDeclaration, () -> Void, Void>(mock: self, invocation: invocation)
  }
}

public protocol BirdAbstractMockType {}

/// Initialize a protocol mock of `Sample.Bird`.
public func mock(_ type: Sample.Bird.Protocol, file: StaticString = #file, line: UInt = #line) -> BirdAbstractMockType {
  return BirdMock(sourceLocation: SourceLocation(file, line))
}

/// Initialize a protocol mock of `Sample.Bird`.
public func mock<__ReturnType: BirdAbstractMockType>(_ type: Sample.Bird.Protocol, file: StaticString = #file, line: UInt = #line) -> __ReturnType {
  return BirdMock(sourceLocation: SourceLocation(file, line)) as! __ReturnType
}

/// Create a dummy object of `Sample.Bird`.
public func dummy(_ type: Sample.Bird.Protocol, file: StaticString = #file, line: UInt = #line) -> BirdMock {
  return BirdMock(sourceLocation: SourceLocation(file, line))
}

/// Initialize a protocol mock of `Sample.Bird`.
@available(swift, obsoleted: 3.0, renamed: "dummy", message: "Store the mock in a variable of type 'BirdMock' or use 'dummy(Bird.self)' to create a non-mockable dummy object")
public func mock<__ReturnType>(_ type: Sample.Bird.Protocol) -> __ReturnType { fatalError() }

3. The expected mocking code that should be generated (or a description)

Not sure yet.

Framework Bugs

Please provide a minimal example of your unit testing code, including any errors.

func testBird() {
    let bird = mock(Bird.self)

    (bird as Bird).fly()
    // 'BirdAbstractMockType' is not convertible to 'Bird'; did you mean to use 'as!' to force downcast?

    verify(bird.fly()).wasCalled()
    // Value of type 'BirdAbstractMockType' has no member 'fly'
}

Environment

• Mockingbird CLI version 0.11.0
• Xcode 11.4 and macOS 10.15.4
• Swift version Apple Swift version 5.2 (swiftlang-1103.0.32.1 clang-1103.0.32.29)
• Installation method CocoaPods

[Pavel Ivashkov]

This is unfortunate, and breaks README promise:

let bird: BirdMock = mock(Bird.self)  // The concrete type is `BirdMock`
let inferredBird = mock(Bird.self)    // but type inference also works

[Andrew Chang]

Thanks for reporting, this was an oversight on my part. Seems like there is no easy fix, so I’ll revert the initializer changes in 0.11.1.

As a workaround, declaring explicit type annotations using the concrete mock type, e.g. SomeTypeMock, should make the compiler happy again.