Add CheckBackground tests

osu.Game.Tests/Editing/Checks/CheckBackgroundTest.cs

@@ -0,0 +1,73 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Collections.Generic;
+using System.Linq;
+using NUnit.Framework;
+using osu.Game.Beatmaps;
+using osu.Game.Rulesets.Edit.Checks;
+using osu.Game.Rulesets.Objects;
+
+namespace osu.Game.Tests.Editing.Checks
+{
+    [TestFixture]
+    public class CheckBackgroundTest
+    {
+        private CheckBackground check;
+        private IBeatmap beatmap;
+
+        [SetUp]
+        public void Setup()
+        {
+            check = new CheckBackground();
+            beatmap = new Beatmap<HitObject>
+            {
+                BeatmapInfo = new BeatmapInfo
+                {
+                    Metadata = new BeatmapMetadata { BackgroundFile = "abc123.jpg" },
+                    BeatmapSet = new BeatmapSetInfo
+                    {
+                        Files = new List<BeatmapSetFileInfo>(new []
+                        {
+                            new BeatmapSetFileInfo { Filename = "abc123.jpg" }
+                        })
+                    }
+                }
+            };
+        }
+
+        [Test]
+        public void TestBackgroundSetAndInFiles()
+        {
+            var issues = check.Run(beatmap);
+
+            Assert.That(!issues.Any());
+        }
+
+        [Test]
+        public void TestBackgroundSetAndNotInFiles()
+        {
+            beatmap.BeatmapInfo.BeatmapSet.Files.Clear();
+
+            var issues = check.Run(beatmap).ToList();
+            var issue = issues.FirstOrDefault();
+
+            Assert.That(issues.Count == 1);
+            Assert.That(issue != null);
+            Assert.That(issue.Template.Equals(check.PossibleTemplates.ElementAt(1)));
+        }
+
+        [Test]
+        public void TestBackgroundNotSet()
+        {
+            beatmap.Metadata.BackgroundFile = null;
+
+            var issues = check.Run(beatmap).ToList();
+            var issue = issues.FirstOrDefault();
+
+            Assert.That(issues.Count == 1);
+            Assert.That(issue != null);
+            Assert.That(issue.Template.Equals(check.PossibleTemplates.ElementAt(0)));
+        }
+    }
+}