Add a SwiftUI unit test target

GoogleSignInSwift.podspec

@@ -24,4 +24,14 @@ Pod::Spec.new do |s|
     'SwiftUI',
   ]
   s.dependency 'GoogleSignIn', '~> 6.2'
+  s.test_spec 'unit' do |unit_tests|
+    unit_tests.platforms = {
+      :ios => ios_deployment_target,
+      :osx => macos_deployment_target,
+    }
+    unit_tests.source_files = [
+      'GoogleSignInSwift/Tests/Unit/*.swift',
+    ]
+    unit_tests.requires_app_host = false
+  end
 end

GoogleSignInSwift/Tests/Unit/GoogleSignInButtonStylingTests.swift

@@ -0,0 +1,98 @@
+/*
+ * Copyright 2022 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import XCTest
+@testable import GoogleSignInSwift
+
+@available(iOS 13.0, macOS 10.15, *)
+class GoogleSignInButtonStylingTests: XCTestCase {
+  private typealias ButtonViewModelInfo = (
+    scheme: GoogleSignInButtonColorScheme,
+    style: GoogleSignInButtonStyle,
+    state: GoogleSignInButtonState
+  )
+
+  func testThatViewModelGetsCorrectColor() {
+    let stylingTuples: [ButtonViewModelInfo] = [
+      (.light, .standard, .normal),
+      (.light, .wide, .normal),
+      (.light, .icon, .normal),
+
+      (.light, .standard, .pressed),
+      (.light, .wide, .pressed),
+      (.light, .icon, .pressed),
+
+      (.light, .standard, .disabled),
+      (.light, .wide, .disabled),
+      (.light, .icon, .disabled),
+
+      (.dark, .standard, .normal),
+      (.dark, .wide, .normal),
+      (.dark, .icon, .normal),
+
+      (.dark, .standard, .pressed),
+      (.dark, .wide, .pressed),
+      (.dark, .icon, .pressed),
+
+      (.dark, .standard, .disabled),
+      (.dark, .wide, .disabled),
+      (.dark, .icon, .disabled),
+    ]
+
+    for styleTuple in stylingTuples {
+      buttonViewModelAndColor(
+        scheme: styleTuple.scheme,
+        style: styleTuple.style,
+        state: styleTuple.state
+      ) { viewModel, colors in
+        XCTAssertEqual(
+          viewModel.buttonStyle.colors.foregroundColor,
+          colors.foregroundColor
+        )
+        XCTAssertEqual(
+          viewModel.buttonStyle.colors.backgroundColor,
+          colors.backgroundColor
+        )
+        XCTAssertEqual(
+          viewModel.buttonStyle.colors.iconColor,
+          colors.iconColor
+        )
+        XCTAssertEqual(
+          viewModel.buttonStyle.colors.iconBorderColor,
+          colors.iconBorderColor
+        )
+      }
+    }
+  }
+}
+
+@available(iOS 13.0, macOS 10.15, *)
+extension GoogleSignInButtonStylingTests {
+  func buttonViewModelAndColor(
+    scheme: GoogleSignInButtonColorScheme,
+    style: GoogleSignInButtonStyle,
+    state: GoogleSignInButtonState,
+    completion: (GoogleSignInButtonViewModel, SignInButtonColor) -> Void
+  ) {
+    let vm = GoogleSignInButtonViewModel(
+      scheme: scheme,
+      style: style,
+      state: state
+    )
+    let bc = SignInButtonColor(scheme: scheme, state: state)
+    completion(vm, bc)
+  }
+}

Package.swift

@@ -114,5 +114,10 @@ let package = Package(
         .define("GID_SDK_VERSION", to: googleSignInVersion),
       ]
     ),
+    .testTarget(
+      name: "GoogleSignInSwift-UnitTests",
+      dependencies: ["GoogleSignInSwift"],
+      path: "GoogleSignInSwift/Tests/Unit"
+    )
   ]
 )

Samples/Swift/DaysUntilBirthday/Podfile

@@ -1,5 +1,5 @@
 pod 'GoogleSignIn', :path => '../../../', :testspecs => ['unit']
-pod 'GoogleSignInSwift', :path => '../../../'
+pod 'GoogleSignInSwift', :path => '../../../', :testspecs => ['unit']
 project 'DaysUntilBirthdayForPod.xcodeproj'
 
 target 'DaysUntilBirthdayForPod(iOS)' do