Support clearing the text in the PowerShell console by clicking the Clear button.

src/AddIns/BackendBindings/Scripting/Project/Src/IScriptingConsole.cs

@@ -11,6 +11,7 @@ namespace ICSharpCode.Scripting
 				
 		bool ScrollToEndWhenTextWritten { get; set; }
 		
+		void Clear();
 		void SendLine(string line);
 		void SendText(string text);
 		void WriteLine();

src/AddIns/BackendBindings/Scripting/Project/Src/IScriptingConsoleTextEditor.cs

@@ -28,6 +28,11 @@ namespace ICSharpCode.Scripting
 		/// </summary>
 		void Append(string text);
 		
+		/// <summary>
+		/// Clears all the text in the text editor.
+		/// </summary>
+		void Clear();
+		
 		/// <summary>
 		/// Replaces the text at the specified index on the current line with the specified text.
 		/// </summary>

src/AddIns/BackendBindings/Scripting/Project/Src/ScriptingConsole.cs

@@ -357,5 +357,10 @@ namespace ICSharpCode.Scripting
 		{
 			return textEditor.GetMaximumVisibleColumns();
 		}
+		
+		public void Clear()
+		{
+			textEditor.Clear();
+		}
 	}
 }

src/AddIns/BackendBindings/Scripting/Project/Src/ScriptingConsoleTextEditor.cs

@@ -183,5 +183,10 @@ namespace ICSharpCode.Scripting
 				textEditor.FontWeight,
 				textEditor.FontStretch);
 		}
+		
+		public void Clear()
+		{
+			textEditor.Clear();
+		}
 	}
 }

src/AddIns/BackendBindings/Scripting/Project/Src/ThreadSafeScriptingConsole.cs

@@ -144,5 +144,15 @@ namespace ICSharpCode.Scripting
 				return (int)dispatcher.Invoke(action);
 			}
 		}
+		
+		public void Clear()
+		{
+			if (dispatcher.CheckAccess()) {
+				nonThreadSafeScriptingConsole.Clear();
+			} else {
+				Action action = Clear;
+				dispatcher.Invoke(action);
+			}
+		}
 	}
 }

src/AddIns/BackendBindings/Scripting/Test/Console/ScriptingConsoleTextEditorTests.cs

@@ -188,5 +188,17 @@ namespace ICSharpCode.Scripting.Tests.Console
 			
 			Assert.AreEqual(expectedText, text);
 		}
+		
+		[Test]
+		public void Clear_TextEditorHasText_RemovesAllTextFromTextEditor()
+		{
+			avalonEditTextEditor.Text = "abc";
+			consoleTextEditor.Clear();
+			
+			string text = avalonEditTextEditor.Text;
+			string expectedText = String.Empty;
+			
+			Assert.AreEqual(expectedText, text);
+		}
 	}
 }

src/AddIns/BackendBindings/Scripting/Test/Console/ScriptingConsoleWriteTests.cs

@@ -83,5 +83,16 @@ namespace ICSharpCode.Scripting.Tests.Console
 		{
 			Assert.IsTrue(TestableScriptingConsole.ScrollToEndWhenTextWritten);
 		}
+		
+		[Test]
+		public void Clear_TextEditorHasText_RemovesAllText()
+		{
+			TestableScriptingConsole.Write("a", ScriptingStyle.Prompt);
+			TestableScriptingConsole.Clear();
+			
+			bool cleared = FakeConsoleTextEditor.IsClearCalled;
+			
+			Assert.IsTrue(cleared);
+		}
 	}
 }

src/AddIns/BackendBindings/Scripting/Test/Console/ThreadSafeScriptingConsoleTests.cs

@@ -410,5 +410,29 @@ namespace ICSharpCode.Scripting.Tests.Console
 			
 			Assert.AreEqual(10, columns);
 		}
+		
+		[Test]
+		public void Clear_DispatcherCheckAccessReturnsTrue_NonThreadSafeScriptingConsoleClearMethodIsCalled()
+		{
+			CreateThreadSafeScriptingConsole();
+			
+			dispatcher.CheckAccessReturnValue = true;
+			threadSafeConsole.Clear();
+			
+			Assert.IsTrue(nonThreadSafeScriptingConsole.IsClearCalled);
+		}
+		
+		[Test]
+		public void Clear_DispatcherCheckAccessReturnsFalse_MethodIsInvoked()
+		{
+			CreateThreadSafeScriptingConsole();
+			
+			dispatcher.CheckAccessReturnValue = false;
+			dispatcher.MethodInvoked = null;
+			
+			threadSafeConsole.Clear();
+			
+			Assert.IsNotNull(dispatcher.MethodInvoked);
+		}
 	}
 }

src/AddIns/BackendBindings/Scripting/Test/Utils/FakeConsoleTextEditor.cs

@@ -207,5 +207,12 @@ namespace ICSharpCode.Scripting.Tests.Utils
 		{
 			return MaximumVisibleColumns;
 		}
+		
+		public bool IsClearCalled;
+		
+		public void Clear()
+		{
+			IsClearCalled = true;
+		}
 	}
 }

src/AddIns/BackendBindings/Scripting/Test/Utils/FakeScriptingConsole.cs

@@ -25,6 +25,7 @@ namespace ICSharpCode.Scripting.Tests.Utils
 		public bool IsReadLineCalled;
 		public bool IsDisposeCalled;
 		public int MaximumVisibleColumns;
+		public bool IsClearCalled;
 		
 		public string LastLinePassedToWriteLine {
 			get { return AllTextPassedToWriteLine[AllTextPassedToWriteLine.Count - 1]; }
@@ -90,5 +91,10 @@ namespace ICSharpCode.Scripting.Tests.Utils
 		{
 			return MaximumVisibleColumns;
 		}
+		
+		public void Clear()
+		{
+			IsClearCalled = true;
+		}
 	}
 }

src/AddIns/Misc/PackageManagement/Project/Src/Scripting/PackageManagementConsoleHost.cs

@@ -69,6 +69,8 @@ namespace ICSharpCode.PackageManagement.Scripting
 		
 		public void Clear()
 		{
+			ScriptingConsole.Clear();
+			WritePrompt();
 		}
 		
 		public void Run()

src/AddIns/Misc/PackageManagement/Test/Src/Scripting/PackageManagementConsoleHostTests.cs

@@ -384,7 +384,7 @@ namespace PackageManagement.Tests.Scripting
 		}
 		
 		[Test]
-		public void ActivePackageSource_ActivePackageSourcechanged_RegisteredPackageSourcesActivePackageSourceIsUpdated()
+		public void ActivePackageSource_ActivePackageSourceChanged_RegisteredPackageSourcesActivePackageSourceIsUpdated()
 		{
 			CreateHost();
 			var expectedPackageSource = new PackageSource("Test");
@@ -394,5 +394,28 @@ namespace PackageManagement.Tests.Scripting
 			
 			Assert.AreEqual(expectedPackageSource, actualPackageSource);
 		}
+		
+		[Test]
+		public void Clear_ConsoleWindowHasOutputText_ScriptingConsoleIsCleared()
+		{
+			CreateHost();
+			host.Clear();
+			
+			bool cleared = scriptingConsole.IsClearCalled;
+			
+			Assert.IsTrue(cleared);
+		}
+		
+		[Test]
+		public void Clear_ConsoleWindowHasOutputText_PromptWritten()
+		{
+			CreateHost();
+			host.Clear();
+			
+			var expectedTextPassedToWrite = new String[] { "PM> "};
+			var actualTextPassedToWrite = scriptingConsole.AllTextPassedToWrite;
+			
+			CollectionAssert.AreEqual(expectedTextPassedToWrite, actualTextPassedToWrite);
+		}
 	}
 }