Fix double-clicking in string interpolation

editor/tools/plugins/com.google.dart.tools.ui_test/src/com/google/dart/tools/ui/internal/text/dart/DartDoubleClickSelectorTest.java

Index: editor/tools/plugins/com.google.dart.tools.ui_test/src/com/google/dart/tools/ui/internal/text/dart/DartDoubleClickSelectorTest.java
diff --git a/editor/tools/plugins/com.google.dart.tools.ui_test/src/com/google/dart/tools/ui/internal/text/dart/DartDoubleClickSelectorTest.java b/editor/tools/plugins/com.google.dart.tools.ui_test/src/com/google/dart/tools/ui/internal/text/dart/DartDoubleClickSelectorTest.java
new file mode 100644
index 0000000000000000000000000000000000000000..175249e6f8f48344a006d58c1ab4ea1d38395a72
--- /dev/null
+++ b/editor/tools/plugins/com.google.dart.tools.ui_test/src/com/google/dart/tools/ui/internal/text/dart/DartDoubleClickSelectorTest.java
@@ -0,0 +1,70 @@
+package com.google.dart.tools.ui.internal.text.dart;
+
+import com.google.dart.engine.ast.CompilationUnit;
+import com.google.dart.engine.parser.ParserTestCase;
+import com.google.dart.tools.ui.internal.text.editor.CompilationUnitEditor;
+
+import org.eclipse.jface.text.Document;
+import org.eclipse.jface.text.IDocument;
+import org.eclipse.swt.graphics.Point;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+public class DartDoubleClickSelectorTest extends ParserTestCase {
+  private static void assertDoubleClickSelection(String content, String clickPattern,
+      String resultContent, int offset) throws Exception {
+    CompilationUnitEditor.AdaptedSourceViewer textViewer = mock(CompilationUnitEditor.AdaptedSourceViewer.class);
+    // mock document
+    IDocument document = new Document(content);
+    when(textViewer.getDocument()).thenReturn(document);
+    // mock editor
+    CompilationUnitEditor editor = mock(CompilationUnitEditor.class);
+    when(textViewer.getEditor()).thenReturn(editor);
+    CompilationUnit unit = parseCompilationUnit(content);
+    when(editor.getInputUnit()).thenReturn(unit);
+    // mock double click position
+    int clickOffset = content.indexOf(clickPattern);
+    when(textViewer.getSelectedRange()).thenReturn(new Point(clickOffset, 0));
+    // ask for double click range
+    DartDoubleClickSelector selector = new DartDoubleClickSelector();
+    selector.doubleClicked(textViewer);
+    // validate
+    int resultOffset = offset;
+    if (offset == 0) {
+      resultOffset = content.indexOf(resultContent);
+    }
+    int resultLength = resultContent.length();
+    verify(textViewer).setSelectedRange(resultOffset, resultLength);
+  }
+
+  public void test_dollarIdentifier() throws Exception {
+    String content = "main() { var first$second; }";
+    String clickPattern = "first";
+    String resultContent = "first$second";
+    assertDoubleClickSelection(content, clickPattern, resultContent, 0);
+    clickPattern = "$";
+    assertDoubleClickSelection(content, clickPattern, resultContent, 0);
+    clickPattern = "second";
+    assertDoubleClickSelection(content, clickPattern, resultContent, 0);
+  }
+
+  public void test_interpolation() throws Exception {
+    String content = createSource(//
+        "main() {",
+        "  String first = 'a';",
+        "  String second = 'b';",
+        "  String first$second = 'c';",
+        "  String s = 'xxx$first$second${first$second.length}yyy';",
+        "  print(s); ",
+        "}");
+    int indexOfxxx = content.indexOf("xxx");
+    int indexOfThirdFirst = content.indexOf("first", indexOfxxx);
+    assertDoubleClickSelection(content, "$first", "xxx", 0);
+    assertDoubleClickSelection(content, "first$second$", "first", indexOfThirdFirst);
+    assertDoubleClickSelection(content, "first$second.", "first$second.length", 0);
+    assertDoubleClickSelection(content, "{first$", "${first$second.length}", 0);
+    assertDoubleClickSelection(content, "yyy", "first$second.length", 0);
+  }
+}