Add a basic NaN control point test for LegacyBeatmapDecoder

osu.Game.Tests/Beatmaps/Formats/LegacyBeatmapDecoderTest.cs

@@ -919,5 +919,32 @@ namespace osu.Game.Tests.Beatmaps.Formats
                 Assert.That(controlPoints[1].Position, Is.Not.EqualTo(Vector2.Zero));
             }
         }
+
+        [Test]
+        public void TestNaNControlPoints()
+        {
+            var decoder = new LegacyBeatmapDecoder { ApplyOffsets = false };
+
+            using (var resStream = TestResources.OpenResource("nan-control-points.osu"))
+            using (var stream = new LineBufferedReader(resStream))
+            {
+                var controlPoints = (LegacyControlPointInfo)decoder.Decode(stream).ControlPointInfo;
+
+                Assert.That(controlPoints.TimingPoints.Count, Is.EqualTo(1));
+                Assert.That(controlPoints.DifficultyPoints.Count, Is.EqualTo(3));
+
+                Assert.That(controlPoints.TimingPointAt(1000).BeatLength, Is.EqualTo(500));
+
+                Assert.That(controlPoints.DifficultyPointAt(1000).SliderVelocity, Is.EqualTo(1));
+                Assert.That(controlPoints.DifficultyPointAt(2000).SliderVelocity, Is.EqualTo(1));
+                Assert.That(controlPoints.DifficultyPointAt(3000).SliderVelocity, Is.EqualTo(1));
+
+#pragma warning disable 618
+                Assert.That(((LegacyBeatmapDecoder.LegacyDifficultyControlPoint)controlPoints.DifficultyPointAt(1000)).GenerateTicks, Is.True);
+                Assert.That(((LegacyBeatmapDecoder.LegacyDifficultyControlPoint)controlPoints.DifficultyPointAt(2000)).GenerateTicks, Is.False);
+                Assert.That(((LegacyBeatmapDecoder.LegacyDifficultyControlPoint)controlPoints.DifficultyPointAt(3000)).GenerateTicks, Is.True);
+#pragma warning restore 618
+            }
+        }
     }
 }

osu.Game.Tests/Resources/nan-control-points.osu

@@ -0,0 +1,15 @@
+osu file format v14
+
+[TimingPoints]
+
+// NaN bpm (should be rejected)
+0,NaN,4,2,0,100,1,0
+
+// 120 bpm
+1000,500,4,2,0,100,1,0
+
+// NaN slider velocity
+2000,NaN,4,3,0,100,0,1
+
+// 1.0x slider velocity
+3000,-100,4,3,0,100,0,1