Add tests for EncoderValidator

* Add support for ffmpeg 4.2
* Parse the complete ffmpeg version instead of only the first 2 digits
* Make max and min version optional
* Remove max limitation (for now)
* Style improvements

tests/Jellyfin.MediaEncoding.Tests/EncoderValidatorTests.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using MediaBrowser.MediaEncoding.Encoder;
+using Microsoft.Extensions.Logging.Abstractions;
+using Xunit;
+
+namespace Jellyfin.MediaEncoding.Tests
+{
+    public class EncoderValidatorTests
+    {
+        private class GetFFmpegVersionTestData : IEnumerable<object[]>
+        {
+            public IEnumerator<object[]> GetEnumerator()
+            {
+                yield return new object[] { EncoderValidatorTestsData.FFmpegV42Output, new Version(4, 2) };
+                yield return new object[] { EncoderValidatorTestsData.FFmpegV404Output, new Version(4, 0, 4) };
+            }
+
+            IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
+        }
+
+        [Theory]
+        [ClassData(typeof(GetFFmpegVersionTestData))]
+        public void GetFFmpegVersionTest(string versionOutput, Version version)
+        {
+            Assert.Equal(version, EncoderValidator.GetFFmpegVersion(versionOutput));
+        }
+
+        [Theory]
+        [InlineData(EncoderValidatorTestsData.FFmpegV42Output, true)]
+        [InlineData(EncoderValidatorTestsData.FFmpegV404Output, true)]
+        public void ValidateVersionInternalTest(string versionOutput, bool valid)
+        {
+            var val = new EncoderValidator(new NullLogger<EncoderValidatorTests>());
+            Assert.Equal(valid, val.ValidateVersionInternal(versionOutput));
+        }
+    }
+}