Fixed test of drawing events

Issue #300 Fixed test of drawing events on spectrograms. Test now uses the new image comparison facility.
Set the event name to empty string in order to prevent test failing due to writing of poorly anti-aliased text.
Returned font type to the original.
Included new expected events image in Fixtures.

src/AudioAnalysisTools/AcousticEvent.cs

@@ -477,8 +477,7 @@ public void DrawEvent<T>(Image<T> imageToReturn, double framesPerSecond, double
             imageToReturn.Mutate(g =>
             {
                 g.NoAA().DrawLine(scorePen, t1, y2 - scoreHt, t1, y2 + 1);
-                //g.DrawTextSafe(this.Name, Drawing.Tahoma6, Color.Black, new PointF(t1, y1 - 5));
-                g.DrawTextSafe(this.Name, Drawing.Arial8, Color.Black, new PointF(t1, y1 - 5));
+                g.DrawTextSafe(this.Name, Drawing.Tahoma6, Color.Black, new PointF(t1, y1 - 4));
             });
         }
 

tests/Acoustics.Test/AudioAnalysisTools/AcousticEvents/EventTests.cs

@@ -6,13 +6,14 @@ namespace Acoustics.Test.AudioAnalysisTools.EventStatistics
 {
     using System;
     using System.Collections.Generic;
+    using Acoustics.Test.TestHelpers;
     using global::AudioAnalysisTools;
     using Microsoft.VisualStudio.TestTools.UnitTesting;
     using SixLabors.ImageSharp;
     using SixLabors.ImageSharp.PixelFormats;
 
     [TestClass]
-    public class EventTests
+    public class EventTests : GeneratedImageTest<Rgb24>
     {
         [TestMethod]
         public void TestEventMerging()
@@ -103,26 +104,28 @@ public void TestSonogramWithEventsOverlay()
             // set colour for the events
             foreach (AcousticEvent ev in events)
             {
+                // do not set an event name because text is not drawing anit-aliased at present time.
+                ev.Name = string.Empty;
                 ev.BorderColour = AcousticEvent.DefaultBorderColor;
                 ev.ScoreColour = AcousticEvent.DefaultScoreColor;
                 ev.DrawEvent(substituteSonogram, framesPerSecond, freqBinWidth, height);
             }
 
-            substituteSonogram.Save("C:\\temp\\image.png");
-
-            var redPixel = new Argb32(220, 20, 60);
-            var expectedRed = new Color(redPixel);
-            var greenPixel = new Argb32(0, 255, 0);
-            var expectedGreen = new Color(greenPixel);
-
-            Assert.AreEqual<Color>(expectedRed, substituteSonogram[60, 119]);
-            Assert.AreEqual<Color>(expectedRed, substituteSonogram[70, 122]);
-            Assert.AreEqual<Color>(expectedRed, substituteSonogram[90, 181]);
-            Assert.AreEqual<Color>(expectedRed, substituteSonogram[36, 232]);
-            Assert.AreEqual<Color>(expectedRed, substituteSonogram[56, 69]);
-
-            Assert.AreEqual<Color>(expectedGreen, substituteSonogram[10, 72]);
-            Assert.AreEqual<Color>(expectedGreen, substituteSonogram[70, 217]);
+            substituteSonogram.Save("C:\\temp\\EventTests_SuperimposeEventsOnImage.png");
+
+            this.Actual = substituteSonogram;
+            /*
+            var pattern = @"
+⬇150
+E100R50
+48×E100RE48R
+E100R50
+";
+            this.Expected = TestImage.Create(width: 100, height: 100, Color.Black, pattern);
+            */
+
+            this.Expected = Image.Load<Rgb24>(PathHelper.ResolveAssetPath("EventTests_SuperimposeEventsOnImage.png"));
+            this.AssertImagesEqual();
         }
     }
 }