(belated) Tests for CompilationUnitElement.getElementAt().

pkg/analyzer/test/generated/element_test.dart

Index: pkg/analyzer/test/generated/element_test.dart
diff --git a/pkg/analyzer/test/generated/element_test.dart b/pkg/analyzer/test/generated/element_test.dart
index e8069dcc5ab6b4914ee87f32bb891f07e2b35277..4e8041de7a358abac556d23de1d1d8c78e5c51ab 100644
--- a/pkg/analyzer/test/generated/element_test.dart
+++ b/pkg/analyzer/test/generated/element_test.dart
@@ -916,6 +916,94 @@ abstract class A<K, V> = Object with MapMixin<K, V>;
 
 @reflectiveTest
 class CompilationUnitElementImplTest extends EngineTestCase {
+  void test_getElementAt() {
+    AnalysisContextHelper contextHelper = new AnalysisContextHelper();
+    AnalysisContext context = contextHelper.context;
+    String code = r'''
+class A {
+  int field;
+}
+main() {
+  int localVar = 42;
+}
+''';
+    Source libSource = contextHelper.addSource("/my_lib.dart", code);
+    // prepare library/unit elements
+    LibraryElement libraryElement = context.computeLibraryElement(libSource);
+    CompilationUnitElement unitElement = libraryElement.definingCompilationUnit;
+    // A
+    ClassElement elementA;
+    {
+      int offset = code.indexOf('A {');
+      elementA = unitElement.getElementAt(offset);
+      expect(elementA, isNotNull);
+      expect(elementA.enclosingElement, unitElement);
+      expect(elementA.name, 'A');
+    }
+    // A.field
+    {
+      int offset = code.indexOf('field;');
+      FieldElement element = unitElement.getElementAt(offset);
+      expect(element, isNotNull);
+      expect(element.enclosingElement, elementA);
+      expect(element.name, 'field');
+    }
+    // main
+    FunctionElement mainElement;
+    {
+      int offset = code.indexOf('main() {');
+      mainElement = unitElement.getElementAt(offset);
+      expect(mainElement, isNotNull);
+      expect(mainElement.enclosingElement, unitElement);
+      expect(mainElement.name, 'main');
+    }
+    // main.localVar
+    {
+      int offset = code.indexOf('localVar');
+      LocalVariableElement element = unitElement.getElementAt(offset);
+      expect(element, isNotNull);
+      expect(element.enclosingElement, mainElement);
+      expect(element.name, 'localVar');
+    }
+    // null
+    expect(unitElement.getElementAt(1000), isNull);
+  }
+
+  void test_getElementAt_multipleUnitsInLibrary() {
+    AnalysisContextHelper contextHelper = new AnalysisContextHelper();
+    AnalysisContext context = contextHelper.context;
+    Source libSource = contextHelper.addSource("/my_lib.dart", r'''
+library my_lib;
+part 'unit_a.dart';
+part 'unit_b.dart';
+''');
+    Source unitSourceA =
+        contextHelper.addSource("/unit_a.dart", 'part of my_lib;class A {}');
+    Source unitSourceB =
+        contextHelper.addSource("/unit_b.dart", 'part of my_lib;class B {}');
+    int offset = 'part of my_lib;class A {}'.indexOf('A {}');
+    // prepare library/unit elements
+    context.computeLibraryElement(libSource);
+    CompilationUnitElement unitElementA =
+        context.getCompilationUnitElement(unitSourceA, libSource);
+    CompilationUnitElement unitElementB =
+        context.getCompilationUnitElement(unitSourceB, libSource);
+    // A
+    {
+      ClassElement element = unitElementA.getElementAt(offset);
+      expect(element, isNotNull);
+      expect(element.enclosingElement, unitElementA);
+      expect(element.name, 'A');
+    }
+    // B
+    {
+      ClassElement element = unitElementB.getElementAt(offset);
+      expect(element, isNotNull);
+      expect(element.enclosingElement, unitElementB);
+      expect(element.name, 'B');
+    }
+  }
+
   void test_getEnum_declared() {
     TestTypeProvider typeProvider = new TestTypeProvider();
     CompilationUnitElementImpl unit =