Fix regression in beAnInstanceOf (#1174)

beAnInstanceOf was not correctly matching when an exact type as was expected was given.
This fixes that by emulating the previous typing of beAnInstanceOf while still working when used as a submatcher

Author: younata

Sources/Nimble/Matchers/BeAnInstanceOf.swift

@@ -5,7 +5,7 @@ public func beAnInstanceOf<T, U>(_ expectedType: T.Type) -> Matcher<U> {
     let errorMessage = "be an instance of \(String(describing: expectedType))"
     return Matcher.define { actualExpression in
         let instance = try actualExpression.evaluate()
-        guard let validInstance = instance else {
+        guard let validInstance: Any = instance else {
             return MatcherResult(
                 status: .doesNotMatch,
                 message: .expectedActualValueTo(errorMessage)

Tests/NimbleTests/Matchers/BeAKindOfTest.swift

@@ -28,16 +28,25 @@ final class BeAKindOfSwiftTest: XCTestCase {
         expect(testProtocolClass).to(beAKindOf(TestProtocol.self))
         expect(testProtocolClass).toNot(beAKindOf(TestStructConformingToProtocol.self))
 
+        expect(testProtocolClass as TestProtocol).to(beAKindOf(TestClassConformingToProtocol.self))
+        expect(testProtocolClass as TestProtocol).to(beAKindOf(TestProtocol.self))
+        expect(testProtocolClass as TestProtocol).toNot(beAKindOf(TestStructConformingToProtocol.self))
+
         let testProtocolStruct = TestStructConformingToProtocol()
         expect(testProtocolStruct).to(beAKindOf(TestStructConformingToProtocol.self))
         expect(testProtocolStruct).to(beAKindOf(TestProtocol.self))
         expect(testProtocolStruct).toNot(beAKindOf(TestClassConformingToProtocol.self))
+
+        expect(testProtocolStruct as TestProtocol).to(beAKindOf(TestStructConformingToProtocol.self))
+        expect(testProtocolStruct as TestProtocol).to(beAKindOf(TestProtocol.self))
+        expect(testProtocolStruct as TestProtocol).toNot(beAKindOf(TestClassConformingToProtocol.self))
     }
 
     func testNestedMatchers() {
         // This test is successful if it even compiles.
-        let result: Result<Int, Error> = .success(1)
-        expect(result).to(beSuccess(beAKindOf(Int.self)))
+        expect(Result<Int, Error>.success(1)).to(beSuccess(beAKindOf(Int.self)))
+        expect(Result<TestProtocol, Error>.success(TestClassConformingToProtocol())).to(beSuccess(beAKindOf(TestClassConformingToProtocol.self)))
+        expect(Result<TestProtocol, Error>.success(TestClassConformingToProtocol())).to(beSuccess(beAKindOf(TestProtocol.self)))
     }
 
     func testFailureMessages() {

Tests/NimbleTests/Matchers/BeAnInstanceOfTest.swift

@@ -30,16 +30,25 @@ final class BeAnInstanceOfTest: XCTestCase {
         expect(testProtocolClass).toNot(beAnInstanceOf(TestProtocol.self))
         expect(testProtocolClass).toNot(beAnInstanceOf(TestStructConformingToProtocol.self))
 
+        expect(testProtocolClass as TestProtocol).to(beAnInstanceOf(TestClassConformingToProtocol.self))
+        expect(testProtocolClass as TestProtocol).toNot(beAnInstanceOf(TestProtocol.self))
+        expect(testProtocolClass as TestProtocol).toNot(beAnInstanceOf(TestStructConformingToProtocol.self))
+
         let testProtocolStruct = TestStructConformingToProtocol()
         expect(testProtocolStruct).to(beAnInstanceOf(TestStructConformingToProtocol.self))
         expect(testProtocolStruct).toNot(beAnInstanceOf(TestProtocol.self))
         expect(testProtocolStruct).toNot(beAnInstanceOf(TestClassConformingToProtocol.self))
+
+        expect(testProtocolStruct as TestProtocol).to(beAnInstanceOf(TestStructConformingToProtocol.self))
+        expect(testProtocolStruct as TestProtocol).toNot(beAnInstanceOf(TestProtocol.self))
+        expect(testProtocolStruct as TestProtocol).toNot(beAnInstanceOf(TestClassConformingToProtocol.self))
     }
 
     func testNestedMatchers() {
         // This test is successful if it even compiles.
-        let result: Result<Int, Error> = .success(1)
-        expect(result).to(beSuccess(beAnInstanceOf(Int.self)))
+        expect(Result<Int, Error>.success(1)).to(beSuccess(beAnInstanceOf(Int.self)))
+        expect(Result<TestProtocol, Error>.success(TestClassConformingToProtocol())).to(beSuccess(beAnInstanceOf(TestClassConformingToProtocol.self)))
+        expect(Result<TestProtocol, Error>.success(TestClassConformingToProtocol())).toNot(beSuccess(beAnInstanceOf(TestProtocol.self)))
     }
 
     func testFailureMessages() {