Added Snapshot tests

.gitignore

@@ -3,3 +3,5 @@
 /Packages
 /*.xcodeproj
 xcuserdata/
+/.swiftpm/xcode
+Package.resolved

Package.swift

@@ -15,8 +15,11 @@ let package = Package(
             targets: ["SegmentedPicker"]),
     ],
     dependencies: [
-        // Dependencies declare other packages that this package depends on.
-        // .package(url: /* package url */, from: "1.0.0"),
+        .package(
+            url: "https://github.com/pointfreeco/swift-snapshot-testing",
+            from: "1.12.0"
+        )
+
     ],
     targets: [
         // Targets are the basic building blocks of a package. A target can define a module or a test suite.
@@ -26,6 +29,9 @@ let package = Package(
             dependencies: []),
         .testTarget(
             name: "SegmentedPickerTests",
-            dependencies: ["SegmentedPicker"]),
+            dependencies: [
+                "SegmentedPicker",
+                .product(name: "SnapshotTesting", package: "swift-snapshot-testing")
+            ]),
     ]
 )

Tests/SegmentedPickerTests/CapsuleSelectionViewTests.swift

@@ -0,0 +1,23 @@
+//
+//  File.swift
+//  
+//
+//  Created by Sergey Kazakov on 15/06/2024.
+//
+
+import SwiftUI
+import XCTest
+import SnapshotTesting
+@testable import SegmentedPicker
+
+final class CapsuleSelectionViewTests: XCTestCase {
+    func test_WhenSelectionIsNotProvided_SelectionIsNotVisible_Snapshot() {
+        let view = CapsuleSelectionView(titles: ["One", "Two", "Three"])
+        assertSnapshots(of: view, as: [.image(layout: .device(config: .iPhone13Pro))])
+    }
+
+    func test_WhenSelectionIsProvided_SelectionIsVisible_Snapshot() {
+        let view = CapsuleSelectionView(titles: ["One", "Two", "Three"], selectedIndex: 1)
+        assertSnapshots(of: view, as: [.image(layout: .device(config: .iPhone13Pro))])
+    }
+}

Tests/SegmentedPickerTests/TestViews/CapsuleSelectionView.swift

@@ -0,0 +1,36 @@
+//
+//  File.swift
+//  
+//
+//  Created by Sergey Kazakov on 15/06/2024.
+//
+
+import SwiftUI
+@testable import SegmentedPicker
+
+struct CapsuleSelectionView: View {
+   let titles: [String]
+       @State var selectedIndex: Int?
+
+   var body: some View {
+       VStack {
+           SegmentedPicker(
+               titles,
+               selectedIndex: Binding(
+                   get: { selectedIndex },
+                   set: { selectedIndex = $0 }),
+               content: { item, isSelected in
+                   Text(item)
+                       .foregroundColor(isSelected ? Color.white : Color.gray )
+                       .padding(.horizontal, 16)
+                       .padding(.vertical, 8)
+               },
+               selection: {
+                   Capsule()
+                       .fill(Color.gray)
+               })
+       }
+
+       Spacer()
+   }
+}

Tests/SegmentedPickerTests/TestViews/UnderlineSelectionView.swift

@@ -0,0 +1,39 @@
+//
+//  File.swift
+//  
+//
+//  Created by Sergey Kazakov on 15/06/2024.
+//
+
+import SwiftUI
+@testable import SegmentedPicker
+
+struct UnderlineSelectionView: View {
+    let titles: [String]
+    @State var selectedIndex: Int?
+
+    var body: some View {
+        VStack {
+            SegmentedPicker(
+                titles,
+                selectedIndex: Binding(
+                    get: { selectedIndex },
+                    set: { selectedIndex = $0 }),
+                selectionAlignment: .bottom,
+                content: { item, isSelected in
+                    Text(item)
+
+                        .foregroundColor(isSelected ? Color.black : Color.gray )
+                        .padding(.horizontal, 16)
+                        .padding(.vertical, 8)
+                },
+                selection: {
+                    VStack(spacing: 0) {
+                        Spacer()
+                        Color.black.frame(height: 1)
+                    }
+                })
+            Spacer()
+        }
+    }
+}

Tests/SegmentedPickerTests/UnderlineSelectionViewTests.swift

@@ -0,0 +1,23 @@
+//
+//  File.swift
+//
+//
+//  Created by Sergey Kazakov on 15/06/2024.
+//
+
+import SwiftUI
+import XCTest
+import SnapshotTesting
+@testable import SegmentedPicker
+
+final class UnderlineSelectionViewTest: XCTestCase {
+    func test_WhenSelectionIsNotProvided_SelectionIsNotVisible_Snapshot() {
+        let view = UnderlineSelectionView(titles: ["One", "Two", "Three"])
+        assertSnapshots(of: view, as: [.image(layout: .device(config: .iPhone13Pro))])
+    }
+
+    func test_WhenSelectionIsProvided_SelectionIsVisible_Snapshot() {
+        let view = UnderlineSelectionView(titles: ["One", "Two", "Three"], selectedIndex: 1)
+        assertSnapshots(of: view, as: [.image(layout: .device(config: .iPhone13Pro))])
+    }
+}