Emit a ModelTokensChangedEvent for all the lines when setting a null grammar

src/TextMateSharp.Tests/Model/TMModelTests.cs

@@ -66,6 +66,48 @@ public void TMModel_Should_Not_Parse_Setting_A_Null_Grammar()
                 It.IsAny<ModelTokensChangedEvent>()), Times.Never());
         }
 
+        [Test]
+        public void TMModel_Should_Emit_ModelTokensChangedEvent_To_Clean_Highlighted_Lines_When_Setting_A_Null_Grammar_After_Having_Another_Grammar()
+        {
+            ModelLinesMock modelLines = new ModelLinesMock(new string[] { "line 1", "line 2", "line 3" });
+
+            TMModel tmModel = new TMModel(modelLines);
+
+            Mock<IModelTokensChangedListener> changesListenerMock = new Mock<IModelTokensChangedListener>(
+                MockBehavior.Strict);
+            changesListenerMock.Setup(
+                c => c.ModelTokensChanged(It.IsAny<ModelTokensChangedEvent>()));
+
+            RegistryOptions options = new RegistryOptions(ThemeName.DarkPlus);
+            Registry.Registry registry = new Registry.Registry(options);
+            IGrammar grammar = registry.LoadGrammar("source.cs");
+
+            tmModel.SetGrammar(grammar);
+
+            tmModel.AddModelTokensChangedListener(changesListenerMock.Object);
+            tmModel.SetGrammar(null);
+
+            // verify the three lines were invalidated
+            changesListenerMock.Verify(c => c.ModelTokensChanged(
+                It.Is<ModelTokensChangedEvent>(e => IsRangeValid(e, 0, 2))),
+                Times.Once());
+
+        }
+
+        static bool IsRangeValid(ModelTokensChangedEvent e, int fromLine, int toLine)
+        {
+            if (e.Ranges.Count != 1)
+                return false;
+
+            if (e.Ranges[0].FromLineNumber != fromLine)
+                return false;
+
+            if (e.Ranges[0].ToLineNumber != toLine)
+                return false;
+
+            return true;
+        }
+
         class ModelLinesMock : AbstractLineList
         {
             string[] _lines;

src/TextMateSharp/Model/Range.cs

@@ -10,5 +10,11 @@ public Range(int lineNumber)
             FromLineNumber = lineNumber;
             ToLineNumber = lineNumber;
         }
+
+        public Range(int fromLineNumber, int toLineNumber)
+        {
+            FromLineNumber = fromLineNumber;
+            ToLineNumber = toLineNumber;
+        }
     }
 }

src/TextMateSharp/Model/TMModel.cs

@@ -291,6 +291,10 @@ public void SetGrammar(IGrammar grammar)
                     Start();
                     InvalidateLine(0);
                 }
+                else
+                {
+                    Emit(new ModelTokensChangedEvent(new Range(0, _lines.GetNumberOfLines() - 1), this));
+                }
             }
         }