Add snapshot test for markdown images

Author: gonzalezreal

Package.swift

@@ -55,7 +55,10 @@ let package = Package(
                 "MarkdownUI",
                 "SnapshotTesting",
             ],
-            exclude: ["__Snapshots__"]
+            exclude: [
+                "__Snapshots__",
+                "__Fixtures__",
+            ]
         ),
     ]
 )

Sources/MarkdownUI/Shared/Markdown+Environment.swift

@@ -1,5 +1,6 @@
 #if canImport(SwiftUI) && !os(watchOS)
 
+    import CombineSchedulers
     import SwiftUI
 
     @available(macOS 10.15, iOS 13.0, tvOS 13.0, *)
@@ -28,6 +29,11 @@
             get { self[MarkdownStyleKey.self] }
             set { self[MarkdownStyleKey.self] = newValue }
         }
+
+        var markdownScheduler: AnySchedulerOf<DispatchQueue> {
+            get { self[MarkdownSchedulerKey.self] }
+            set { self[MarkdownSchedulerKey.self] = newValue }
+        }
     }
 
     @available(macOS 10.15, iOS 13.0, tvOS 13.0, *)
@@ -40,4 +46,9 @@
         static let defaultValue: MarkdownStyle = DefaultMarkdownStyle(font: .system(.body))
     }
 
+    @available(macOS 10.15, iOS 13.0, tvOS 13.0, watchOS 6.0, *)
+    private struct MarkdownSchedulerKey: EnvironmentKey {
+        static let defaultValue: AnySchedulerOf<DispatchQueue> = .main
+    }
+
 #endif

Sources/MarkdownUI/Shared/Markdown.swift

@@ -46,7 +46,7 @@
         @Environment(\.markdownBaseURL) private var markdownBaseURL: URL?
         @Environment(\.markdownStyle) private var markdownStyle: MarkdownStyle
         @Environment(\.networkImageLoader) private var imageLoader
-        @Environment(\.networkImageScheduler) private var imageScheduler
+        @Environment(\.markdownScheduler) private var markdownScheduler
 
         @ObservedObject private var store: MarkdownStore
 
@@ -71,7 +71,7 @@
                             .onAppear(
                                 environment: .init(
                                     imageLoader: imageLoader,
-                                    mainQueue: imageScheduler,
+                                    mainQueue: markdownScheduler,
                                     baseURL: markdownBaseURL,
                                     writingDirection: NSWritingDirection(layoutDirection: layoutDirection),
                                     alignment: NSTextAlignment(

Tests/MarkdownUITests/Fixtures.swift

@@ -0,0 +1,21 @@
+#if !os(macOS) && !targetEnvironment(macCatalyst)
+
+    import UIKit
+
+    enum Fixtures {
+        static let anyImageURL = URL(string: "https://picsum.photos/id/237/200/300")!
+
+        // Photo by André Spieker (https://unsplash.com/@andrespieker)
+        static let anyImage = UIImage(
+            data: try! Data(contentsOf: fixtureURL("puppy.jpg"))
+        )!
+    }
+
+    private func fixtureURL(_ fileName: String, file: StaticString = #file) -> URL {
+        URL(fileURLWithPath: "\(file)", isDirectory: false)
+            .deletingLastPathComponent()
+            .appendingPathComponent("__Fixtures__")
+            .appendingPathComponent(fileName)
+    }
+
+#endif

Tests/MarkdownUITests/MarkdownTests.swift

@@ -1,10 +1,11 @@
 #if canImport(SwiftUI) && !os(macOS) && !targetEnvironment(macCatalyst)
 
+    import Combine
     import SnapshotTesting
     import SwiftUI
     import XCTest
 
-    import MarkdownUI
+    @testable import MarkdownUI
 
     @available(iOS 14.0, tvOS 14.0, *)
     final class MarkdownTests: XCTestCase {
@@ -332,6 +333,27 @@
 
             assertSnapshot(matching: view, as: .image(layout: layout), named: platformName)
         }
+
+        func testImage() {
+            let view = TestView(
+                #"""
+                If you want to embed images, this is how you do it:
+
+                ![Puppy](https://picsum.photos/id/237/200/300)
+
+                Photo by André Spieker.
+                """#
+            )
+            .networkImageLoader(
+                .mock(
+                    url: Fixtures.anyImageURL,
+                    withResponse: Just(Fixtures.anyImage).setFailureType(to: Error.self)
+                )
+            )
+            .environment(\.markdownScheduler, .immediate)
+
+            assertSnapshot(matching: view, as: .image(layout: layout), named: platformName)
+        }
     }
 
 #endif