Internal refactoring and testing Diff Editor

app/assets/javascripts/editor/editor_lite.js

@@ -34,15 +34,12 @@ export default class EditorLite {
     monacoEditor.setTheme(theme ? themeName : DEFAULT_THEME);
   }
 
-  static updateModelLanguage(path, instance) {
-    if (!instance) return;
-    const model = instance.getModel();
+  static getModelLanguage(path) {
     const ext = `.${path.split('.').pop()}`;
     const language = monacoLanguages
       .getLanguages()
       .find((lang) => lang.extensions.indexOf(ext) !== -1);
-    const id = language ? language.id : 'plaintext';
-    monacoEditor.setModelLanguage(model, id);
+    return language ? language.id : 'plaintext';
   }
 
   static pushToImportsArray(arr, toImport) {
@@ -113,6 +110,7 @@ export default class EditorLite {
     blobOriginalContent,
     blobGlobalId,
     instance,
+    diff,
   } = {}) {
     if (!instance) {
       return null;
@@ -121,20 +119,28 @@ export default class EditorLite {
     const uri = Uri.file(uriFilePath);
     const existingModel = monacoEditor.getModel(uri);
     const model = existingModel || monacoEditor.createModel(blobContent, undefined, uri);
-    if (!blobOriginalContent) {
+    if (!diff) {
       instance.setModel(model);
-    } else {
-      instance.setModel({
-        original: monacoEditor.createModel(blobOriginalContent, undefined, uri),
-        modified: model,
-      });
+      return model;
     }
-    return instance.getModel();
+    const diffModel = {
+      original: monacoEditor.createModel(
+        blobOriginalContent,
+        EditorLite.getModelLanguage(model.uri.path),
+      ),
+      modified: model,
+    };
+    instance.setModel(diffModel);
+    return diffModel;
   }
 
   static decorateInstance = (inst) => {
     const decoratedInstance = inst;
-    decoratedInstance.updateModelLanguage = (path) => EditorLite.updateModelLanguage(path, inst);
+    decoratedInstance.updateModelLanguage = (path) => {
+      const lang = EditorLite.getModelLanguage(path);
+      const model = decoratedInstance.getModel();
+      return monacoEditor.setModelLanguage(model, lang);
+    };
     decoratedInstance.use = (exts = []) => {
       const extensions = Array.isArray(exts) ? exts : [exts];
       extensions.forEach((extension) => {
@@ -145,6 +151,26 @@ export default class EditorLite {
     return decoratedInstance;
   };
 
+  static onInstanceDisposal(editor, instance, model) {
+    const index = editor.instances.findIndex((inst) => inst === instance);
+    editor.instances.splice(index, 1);
+    const instanceModel = instance.getModel() || model;
+    if (!instanceModel) {
+      return;
+    }
+    if (instance.getEditorType() === EDITOR_TYPE_DIFF) {
+      const { original, modified } = instanceModel;
+      if (original) {
+        original.dispose();
+      }
+      if (modified) {
+        modified.dispose();
+      }
+    } else {
+      instanceModel.dispose();
+    }
+  }
+
   /**
    * Creates a monaco instance with the given options.
    *
@@ -182,28 +208,12 @@ export default class EditorLite {
         blobPath,
         blobContent,
         instance,
+        diff,
       });
     }
 
     instance.onDidDispose(() => {
-      const index = this.instances.findIndex((inst) => inst === instance);
-      this.instances.splice(index, 1);
-      const instanceModel = instance.getModel();
-      if (instanceModel) {
-        if (instance.getEditorType() === EDITOR_TYPE_DIFF) {
-          const { original, modified } = instanceModel;
-          if (original) {
-            original.dispose();
-          }
-          if (modified) {
-            modified.dispose();
-          }
-        } else {
-          instanceModel.dispose();
-        }
-      } else if (model) {
-        model.dispose();
-      }
+      EditorLite.onInstanceDisposal(this, instance, model);
     });
 
     EditorLite.manageDefaultExtensions(instance, el, extensions);
@@ -213,7 +223,7 @@ export default class EditorLite {
   }
 
   createDiffInstance(args) {
-    this.createInstance({
+    return this.createInstance({
       ...args,
       diff: true,
     });

spec/frontend/editor/editor_lite_spec.js

@@ -8,6 +8,7 @@ import {
   EDITOR_LITE_INSTANCE_ERROR_NO_EL,
   URI_PREFIX,
   EDITOR_READY_EVENT,
+  EDITOR_TYPE_DIFF,
 } from '~/editor/constants';
 
 describe('Base editor', () => {
@@ -18,7 +19,7 @@ describe('Base editor', () => {
   const blobContent = 'Foo Bar';
   const blobPath = 'test.md';
   const blobGlobalId = 'snippet_777';
-  const fakeModel = { foo: 'bar', dispose: jest.fn() };
+  const fakeModel = { foo: 'bar', dispose: jest.fn(), uri: { path: blobPath } };
 
   beforeEach(() => {
     setFixtures('<div id="editor" data-editor-loading></div>');
@@ -30,6 +31,9 @@ describe('Base editor', () => {
   afterEach(() => {
     editor.dispose();
     editorEl.remove();
+    monacoEditor.getModels().forEach((model) => {
+      model.dispose();
+    });
   });
 
   const createUri = (...paths) => Uri.file([URI_PREFIX, ...paths].join('/'));
@@ -53,6 +57,7 @@ describe('Base editor', () => {
     let getModel;
     let dispose;
     let modelsStorage;
+    let instanceCreateResponse;
 
     beforeEach(() => {
       setModel = jest.fn();
@@ -60,21 +65,24 @@ describe('Base editor', () => {
       dispose = jest.fn();
       use = jest.fn();
       modelsStorage = new Map();
-    });
-
-    describe('instance of the Code Editor', () => {
-      beforeEach(() => {
       modelSpy = jest.spyOn(monacoEditor, 'createModel').mockImplementation(() => fakeModel);
-        instanceSpy = jest.spyOn(monacoEditor, 'create').mockImplementation(() => ({
+      jest.spyOn(monacoEditor, 'getModel').mockImplementation((uri) => {
+        return modelsStorage.get(uri.path);
+      });
+      instanceCreateResponse = {
         setModel,
         getModel,
         dispose,
         use,
         onDidDispose: jest.fn(),
-        }));
-        jest.spyOn(monacoEditor, 'getModel').mockImplementation((uri) => {
-          return modelsStorage.get(uri.path);
+      };
     });
+
+    describe('instance of the Code Editor', () => {
+      beforeEach(() => {
+        instanceSpy = jest
+          .spyOn(monacoEditor, 'create')
+          .mockImplementation(() => instanceCreateResponse);
       });
 
       it('throws an error if no dom element is supplied', () => {
@@ -111,7 +119,7 @@ describe('Base editor', () => {
         const a = editor.createInstance(defaultArguments);
         const b = editor.createInstance(defaultArguments);
 
-        expect(a === b).toBe(false);
+        expect(a).toBe(b);
         expect(modelSpy).toHaveBeenCalledTimes(1);
       });
 
@@ -146,7 +154,7 @@ describe('Base editor', () => {
         );
       });
 
-      it('disposes instance when the editor is disposed', () => {
+      it('disposes instance when the global editor is disposed', () => {
         editor.createInstance(defaultArguments);
 
         expect(dispose).not.toHaveBeenCalled();
@@ -155,21 +163,26 @@ describe('Base editor', () => {
 
         expect(dispose).toHaveBeenCalled();
       });
+
+      it("removes the disposed instance from the global editor's storage and disposes the associated model", () => {
+        instanceCreateResponse.getModel = jest.fn().mockReturnValue(fakeModel);
+        instanceCreateResponse.getEditorType = jest.fn().mockReturnValue('code');
+        editor.createInstance(defaultArguments);
+
+        expect(editor.instances).toHaveLength(1);
+        expect(fakeModel.dispose).not.toHaveBeenCalled();
+
+        EditorLite.onInstanceDisposal(editor, instanceCreateResponse);
+        expect(editor.instances).toHaveLength(0);
+        expect(fakeModel.dispose).toHaveBeenCalled();
+      });
     });
 
     describe('instance of the Diff Editor', () => {
       beforeEach(() => {
-        modelSpy = jest.spyOn(monacoEditor, 'createModel').mockImplementation(() => fakeModel);
-        instanceSpy = jest.spyOn(monacoEditor, 'createDiffEditor').mockImplementation(() => ({
-          setModel,
-          getModel,
-          dispose,
-          use,
-          onDidDispose: jest.fn(),
-        }));
-        jest.spyOn(monacoEditor, 'getModel').mockImplementation((uri) => {
-          return modelsStorage.get(uri.path);
-        });
+        instanceSpy = jest
+          .spyOn(monacoEditor, 'createDiffEditor')
+          .mockImplementation(() => instanceCreateResponse);
       });
 
       it('Diff Editor goes through the normal path of Code Editor just with the flag ON', () => {
@@ -197,12 +210,33 @@ describe('Base editor', () => {
 
         expect(modelSpy).toHaveBeenCalledTimes(2);
         expect(modelSpy.mock.calls[0]).toEqual([blobContent, undefined, uri]);
-        expect(modelSpy.mock.calls[1]).toEqual([blobOriginalContent, undefined, uri]);
+        expect(modelSpy.mock.calls[1]).toEqual([blobOriginalContent, 'markdown']);
         expect(setModel).toHaveBeenCalledWith({
           original: expect.anything(),
           modified: fakeModel,
         });
       });
+
+      it('correctly disposes the diff editor model', () => {
+        const modifiedModel = fakeModel;
+        const originalModel = { ...fakeModel };
+        instanceCreateResponse.getModel = jest.fn().mockReturnValue({
+          original: originalModel,
+          modified: modifiedModel,
+        });
+
+        instanceCreateResponse.getEditorType = jest.fn().mockReturnValue(EDITOR_TYPE_DIFF);
+        editor.createDiffInstance({ ...defaultArguments, blobOriginalContent });
+
+        expect(editor.instances).toHaveLength(1);
+        expect(originalModel.dispose).not.toHaveBeenCalled();
+        expect(modifiedModel.dispose).not.toHaveBeenCalled();
+
+        EditorLite.onInstanceDisposal(editor, instanceCreateResponse);
+        expect(editor.instances).toHaveLength(0);
+        expect(originalModel.dispose).toHaveBeenCalled();
+        expect(modifiedModel.dispose).toHaveBeenCalled();
+      });
     });
   });
 
@@ -293,6 +327,7 @@ describe('Base editor', () => {
       expect(monacoEditor.getModels()).toHaveLength(2);
 
       inst1.dispose();
+
       expect(inst1.getModel()).toBe(null);
       expect(inst2.getModel()).not.toBe(null);
       expect(editor.instances).toHaveLength(1);