test: make channel logo generator testable

refs #39

ErsatzTV.Core/Images/ChannelLogoGenerator.cs

@@ -10,11 +10,25 @@ public class ChannelLogoGenerator : IChannelLogoGenerator
     public const string GetRoute = "/iptv/logos/gen";
     public const string GetRouteQueryParamName = "text";
 
+    private readonly string _fontPath;
     private readonly ILogger _logger;
+    private readonly string _overlayImagePath;
 
     public ChannelLogoGenerator(
-        ILogger<ChannelLogoGenerator> logger) =>
+        ILogger<ChannelLogoGenerator> logger)
+        : this(logger, DefaultOverlayImagePath(), DefaultFontPath())
+    {
+    }
+
+    public ChannelLogoGenerator(
+        ILogger<ChannelLogoGenerator> logger,
+        string overlayImagePath,
+        string fontPath)
+    {
         _logger = logger;
+        _overlayImagePath = overlayImagePath;
+        _fontPath = fontPath;
+    }
 
     public Either<BaseError, byte[]> GenerateChannelLogo(
         string text,
@@ -29,13 +43,11 @@ public class ChannelLogoGenerator : IChannelLogoGenerator
             canvas.Clear(SKColors.Black);
 
             //etv logo
-            string overlayImagePath = Path.Combine("wwwroot", "images", "ersatztv-500.png");
-            using var overlayImage = SKBitmap.Decode(overlayImagePath);
+            using var overlayImage = SKBitmap.Decode(_overlayImagePath);
             canvas.DrawBitmap(overlayImage, new SKRect(155, 60, 205, 110));
 
             //Custom Font
-            string fontPath = Path.Combine(FileSystemLayout.ResourcesCacheFolder, "Sen.ttf");
-            using var fontTypeface = SKTypeface.FromFile(fontPath);
+            using var fontTypeface = SKTypeface.FromFile(_fontPath);
             var fontSize = 30;
             var font = new SKFont
             {
@@ -80,4 +92,10 @@ public class ChannelLogoGenerator : IChannelLogoGenerator
 
     public static string GenerateChannelLogoUrl(Channel channel) =>
         $"http://localhost:{Settings.StreamingPort}{GetRoute}?{GetRouteQueryParamName}={channel.WebEncodedName}";
+
+    private static string DefaultFontPath() =>
+        Path.Combine(FileSystemLayout.ResourcesCacheFolder, "Sen.ttf");
+
+    private static string DefaultOverlayImagePath() =>
+        Path.Combine("wwwroot", "images", "ersatztv-500.png");
 }