Implement Model-Driven-Views spec for Dart

pkg/mdv_observe/test/list_change_test.dart

+// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:mdv_observe/mdv_observe.dart';
+import 'package:unittest/unittest.dart';
+import 'utils.dart';
+
+// This file contains code ported from:
+// https://github.com/rafaelw/ChangeSummary/blob/master/tests/test.js
+
+main() {
+  // TODO(jmesserly): rename this? Is summarizeListChanges coming back?
+  group('summarizeListChanges', listChangeTests);
+}
+
+// TODO(jmesserly): port or write array fuzzer tests
+listChangeTests() {
+
+  test('sequential adds', () {
+    var model = toObservable([]);
+    model.add(0);
+
+    var summary;
+    var sub = model.changes.listen((r) { summary = _filter(r); });
+
+    model.add(1);
+    model.add(2);
+
+    expect(summary, null);
+    deliverChangeRecords();
+
+    expectChanges(summary, [_delta(1, 0, 2)]);
+  });
+
+  test('List Splice Truncate And Expand With Length', () {
+    var model = toObservable(['a', 'b', 'c', 'd', 'e']);
+
+    var summary;
+    var sub = model.changes.listen((r) { summary = _filter(r); });
+
+    model.length = 2;
+
+    deliverChangeRecords();
+    expectChanges(summary, [_delta(2, 3, 0)]);
+    summary = null;
+
+    model.length = 5;
+
+    deliverChangeRecords();
+    expectChanges(summary, [_delta(2, 0, 3)]);
+  });
+
+  group('List deltas can be applied', () {
+
+    var summary = null;
+
+    observeArray(model) {
+      model.changes.listen((records) { summary = _filter(records); });
+    }
+
+    applyAndCheckDeltas(model, copy) {
+      summary = null;
+      deliverChangeRecords();
+
+      // apply deltas to the copy
+      for (var delta in summary) {
+        copy.removeRange(delta.index, delta.index + delta.removedCount);
+        for (int i = delta.addedCount - 1; i >= 0; i--) {
+          copy.insert(delta.index, model[delta.index + i]);
+        }
+      }
+
+      // Note: compare strings for easier debugging.
+      expect('$copy', '$model', reason: '!!! summary $summary');
+    }
+
+    test('Contained', () {
+      var model = toObservable(['a', 'b']);
+      var copy = model.toList();
+      observeArray(model);
+
+      model.removeAt(1);
+      model.insertAll(0, ['c', 'd', 'e']);
+      model.removeRange(1, 3);
+      model.insert(1, 'f');
+
+      applyAndCheckDeltas(model, copy);
+    });
+
+    test('Delete Empty', () {
+      var model = toObservable([1]);
+      var copy = model.toList();
+      observeArray(model);
+
+      model.removeAt(0);
+      model.insertAll(0, ['a', 'b', 'c']);
+
+      applyAndCheckDeltas(model, copy);
+    });
+
+    test('Right Non Overlap', () {
+      var model = toObservable(['a', 'b', 'c', 'd']);
+      var copy = model.toList();
+      observeArray(model);
+
+      model.removeRange(0, 1);
+      model.insert(0, 'e');
+      model.removeRange(2, 3);
+      model.insertAll(2, ['f', 'g']);
+
+      applyAndCheckDeltas(model, copy);
+    });
+
+    test('Left Non Overlap', () {
+      var model = toObservable(['a', 'b', 'c', 'd']);
+      var copy = model.toList();
+      observeArray(model);
+
+      model.removeRange(3, 4);
+      model.insertAll(3, ['f', 'g']);
+      model.removeRange(0, 1);
+      model.insert(0, 'e');
+
+      applyAndCheckDeltas(model, copy);
+    });
+
+    test('Right Adjacent', () {
+      var model = toObservable(['a', 'b', 'c', 'd']);
+      var copy = model.toList();
+      observeArray(model);
+
+      model.removeRange(1, 2);
+      model.insert(3, 'e');
+      model.removeRange(2, 3);
+      model.insertAll(0, ['f', 'g']);
+
+      applyAndCheckDeltas(model, copy);
+    });
+
+    test('Left Adjacent', () {
+      var model = toObservable(['a', 'b', 'c', 'd']);
+      var copy = model.toList();
+      observeArray(model);
+
+      model.removeRange(2, 4);
+      model.insert(2, 'e');
+
+      model.removeAt(1);
+      model.insertAll(1, ['f', 'g']);
+
+      applyAndCheckDeltas(model, copy);
+    });
+
+    test('Right Overlap', () {
+      var model = toObservable(['a', 'b', 'c', 'd']);
+      var copy = model.toList();
+      observeArray(model);
+
+      model.removeAt(1);
+      model.insert(1, 'e');
+      model.removeAt(1);
+      model.insertAll(1, ['f', 'g']);
+
+      applyAndCheckDeltas(model, copy);
+    });
+
+    test('Left Overlap', () {
+      var model = toObservable(['a', 'b', 'c', 'd']);
+      var copy = model.toList();
+      observeArray(model);
+
+      model.removeAt(2);
+      model.insertAll(2, ['e', 'f', 'g']);
+      // a b [e f g] d
+      model.removeRange(1, 3);
+      model.insertAll(1, ['h', 'i', 'j']);
+      // a [h i j] f g d
+
+      applyAndCheckDeltas(model, copy);
+    });
+
+    test('Prefix And Suffix One In', () {
+      var model = toObservable(['a', 'b', 'c', 'd']);
+      var copy = model.toList();
+      observeArray(model);
+
+      model.insert(0, 'z');
+      model.add('z');
+
+      applyAndCheckDeltas(model, copy);
+    });
+
+    test('Remove First', () {
+      var model = toObservable([16, 15, 15]);
+      var copy = model.toList();
+      observeArray(model);
+
+      model.removeAt(0);
+
+      applyAndCheckDeltas(model, copy);
+    });
+
+    test('Update Remove', () {
+      var model = toObservable(['a', 'b', 'c', 'd']);
+      var copy = model.toList();
+      observeArray(model);
+
+      model.removeAt(2);
+      model.insertAll(2, ['e', 'f', 'g']);  // a b [e f g] d
+      model[0] = 'h';
+      model.removeAt(1);
+
+      applyAndCheckDeltas(model, copy);
+    });
+
+    test('Remove Mid List', () {
+      var model = toObservable(['a', 'b', 'c', 'd']);
+      var copy = model.toList();
+      observeArray(model);
+
+      model.removeAt(2);
+
+      applyAndCheckDeltas(model, copy);
+    });
+  });
+
+  group('edit distance', () {
+    var summary = null;
+
+    observeArray(model) {
+      model.changes.listen((records) { summary = _filter(records); });
+    }
+
+    assertEditDistance(orig, expectDistance) {
+      summary = null;
+      deliverChangeRecords();
+      var actualDistance = 0;
+
+      if (summary != null) {
+        for (var delta in summary) {
+          actualDistance += delta.addedCount + delta.removedCount;
+        }
+      }
+
+      expect(actualDistance, expectDistance);
+    }
+
+    test('add items', () {
+      var model = toObservable([]);
+      observeArray(model);
+      model.addAll([1, 2, 3]);
+      assertEditDistance(model, 3);
+    });
+
+    test('trunacte and add, sharing a contiguous block', () {
+      var model = toObservable(['x', 'x', 'x', 'x', '1', '2', '3']);
+      observeArray(model);
+      model.length = 0;
+      model.addAll(['1', '2', '3', 'y', 'y', 'y', 'y']);
+      // Note: unlike the JS implementation, we don't perform a full diff.
+      // The change records are computed with no regards to the *contents* of
+      // the array. Thus, we get 14 instead of 8.
+      assertEditDistance(model, 14);
+    });
+
+    test('truncate and add, sharing a discontiguous block', () {
+      var model = toObservable(['1', '2', '3', '4', '5']);
+      observeArray(model);
+      model.length = 0;
+      model.addAll(['a', '2', 'y', 'y', '4', '5', 'z', 'z']);
+      // Note: unlike the JS implementation, we don't perform a full diff.
+      // The change records are computed with no regards to the *contents* of
+      // the array. Thus, we get 13 instead of 7.
+      assertEditDistance(model, 13);
+    });
+
+    test('insert at beginning and end', () {
+      var model = toObservable([2, 3, 4]);
+      observeArray(model);
+      model.insert(0, 5);
+      model[2] = 6;
+      model.add(7);
+      assertEditDistance(model, 4);
+    });
+  });
+}
+
+_delta(i, r, a) => new ListChangeRecord(i, removedCount: r, addedCount: a);
+_filter(records) => records.where((r) => r is ListChangeRecord).toList();