AssertEquals via `dump(_:)`. Equate the unequatable!

assertDumpEqual.swift

import func XCTest.XCTAssertEqual

/// Writes the output of `dump(_:)` into a string and returns it.
func dumpToString(_ dumpee: Any) -> String {
    var string = ""
    dump(dumpee, to: &string)

    return string
}

/// Asserts that the `dump(_:)` of the two inputs are equal.
func assertDumpEqual(_ dumpee1: @autoclosure () -> Any, _ dumpee2: @autoclosure () -> Any, _ message: @autoclosure () -> String = "", file: StaticString = #file, line: UInt = #line) {
    XCTAssertEqual(dumpToString(dumpee1()), dumpToString(dumpee2()), file: file, line: line)
}

protocol Unequatable { }

struct MyUnequatable: Unequatable {}

//XCTAssertEqual(MyUnequatable(), MyUnequatable()) // 💥 Compiler error: "Value of protocol type 'Unequatable' cannot conform to 'Equatable'; only struct/enum/class types can conform to protocols"
assertDumpEqual(MyUnequatable(), MyUnequatable()) // ✅

// MARK: - A less trivial example using `Color`.

import struct SwiftUI.Color

// Tuples can't conform to `Equatable`.
let colors1: (Color, Color) = (.red, .red)
let colors2: (Color, Color) = (.red, .green)

// XCTAssertEqual(colors1, colors1) // 💥 Compiler error: "Type '(Color, Color)' cannot conform to 'Equatable'; only struct/enum/class types can conform to protocols"
assertDumpEqual(colors1, colors1) // ✅
assertDumpEqual(colors1, colors2) // ❌