Swift 4 XCTest parameterized test template and sample.

ParameterizedTest.swift

import Foundation
import XCTest

// Parameterized Test Template
class ParameterizedTest : XCTestCase {
    class func createTestCases() -> [ParameterizedTest] {
        fatalError("""
You must override createTestCases() in following way.

    override class func createTestCases() -> [ParameterizedTest] {
        return self.testInvocations.map { YourParameterizedTestSubClass(invocation: $0) }
    }
"""
        )
    }
    class var fixtures: [Any] {
        get {
            fatalError("""
You must override fixtures.
e.g.:
    override class var fixtures: [Any] {
        get {
            return [
                YourTestFixture(3, 9),
                YourTestFixture(4, 16),
            ]
        }
    }
"""
            )
        }
    }

    // Backing field of current fixture
    private var _fixture: Any? = nil

    // Current fixture. Fixture must not be nil.
    final private(set) var fixture : Any {
        get {
            return _fixture!
        }
        set {
            _fixture = newValue
        }
    }

    override class var defaultTestSuite: XCTestSuite {
        let testSuite = XCTestSuite(name: NSStringFromClass(self))
        guard self != ParameterizedTest.self else {
            return testSuite
        }
        for fixture in self.fixtures {
            let testCases = self.createTestCases()
            for testCase in testCases {
                testCase.fixture = fixture
                testSuite.addTest(testCase)
            }
        }
        return testSuite
    }
}

ParameterizedTestSample.swift

import Foundation
import XCTest

// Test sample
struct MathTestFixture {
    let input: [Int]
    let addExpected: Int
    let multExpected: Int

    init(_ input: [Int], _ addExpected: Int, _ multExpected: Int) {
        self.input = input
        self.addExpected = addExpected
        self.multExpected = multExpected
    }
}

class MathTest : ParameterizedTest {
    override class func createTestCases() -> [ParameterizedTest] {
        return self.testInvocations.map { MathTest(invocation: $0) }
    }

    override class var fixtures: [Any] {
        get {
            return [
                MathTestFixture([], 0, 1),
                MathTestFixture([0, 3], 3, 0),
                MathTestFixture([1, 3], 4, 3),
                MathTestFixture([1, 3, 5], 9, 15),
                MathTestFixture([2, 3], 4, 5), // error
            ]
        }
    }

    // Don't run test method. Run test class instead.
    func testAdd() {
        let fixture = self.fixture as! MathTestFixture
        var actual = 0
        fixture.input.forEach { actual += $0 }
        XCTAssertEqual(fixture.addExpected, actual)
    }

    func testMult() {
        let fixture = self.fixture as! MathTestFixture
        var actual = 1
        fixture.input.forEach { actual *= $0 }
        XCTAssertEqual(fixture.multExpected, actual)
    }

}

Is there any way to get this to work when you run the unit tests via the test navigator (or just running a single test suite?)

For some reason, defaultTestSuite's don't seem to get picked up unless the Product -> Test command is used (was in an Apple radar in 2015 as well)