Add more tests

src/vs/editor/test/common/services/modelService.test.ts

@@ -328,6 +328,36 @@ suite('ModelService', () => {
 			assert.equal(model2.getValue(), 'text');
 		});
 	}
+
+	test('does not maintain undo for same resource and different content', () => {
+		const resource = URI.parse('file://test.txt');
+
+		// create a model
+		const model1 = modelService.createModel('text', null, resource);
+		// make an edit
+		model1.pushEditOperations(null, [{ range: new Range(1, 5, 1, 5), text: '1' }], () => [new Selection(1, 5, 1, 5)]);
+		assert.equal(model1.getValue(), 'text1');
+		// dispose it
+		modelService.destroyModel(resource);
+
+		// create a new model with the same content
+		const model2 = modelService.createModel('text2', null, resource);
+		// undo
+		model2.undo();
+		assert.equal(model2.getValue(), 'text2');
+	});
+
+	test('setValue should clear undo stack', () => {
+		const resource = URI.parse('file://test.txt');
+
+		const model = modelService.createModel('text', null, resource);
+		model.pushEditOperations(null, [{ range: new Range(1, 5, 1, 5), text: '1' }], () => [new Selection(1, 5, 1, 5)]);
+		assert.equal(model.getValue(), 'text1');
+
+		model.setValue('text2');
+		model.undo();
+		assert.equal(model.getValue(), 'text2');
+	});
 });
 
 function assertComputeEdits(lines1: string[], lines2: string[]): void {