Initial version of a serialization framework

pkg/serialization/test/serialization_test.dart

+// Copyright (c) 2012, 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.
+
+library serialization_test;
+
+import '../../unittest/lib/unittest.dart';
+import '../lib/serialization.dart';
+import '../lib/src/serialization_helpers.dart';
+import '../lib/src/mirrors_helpers.dart';
+
+part 'test_models.dart';
+
+main() {
+  var p1 = new Person();
+  var a1 = new Address();
+  a1.street = 'N 34th';
+  a1.city = 'Seattle';
+
+  test('Basic extraction of a simple object', () {
+    // TODO(alanknight): Switch these to use literal types. Issue
+    var s = new Serialization()
+        ..addRuleFor(a1).configureForMaps();
+    Map extracted = states(a1, s).first;
+    expect(extracted.length, 4);
+    expect(extracted['street'], 'N 34th');
+    expect(extracted['city'], 'Seattle');
+    expect(extracted['state'], null);
+    expect(extracted['zip'], null);
+    Reader reader = setUpReader(s, extracted);
+    Address a2 = readBackSimple(s, a1, reader);
+    expect(a2.street, 'N 34th');
+    expect(a2.city, 'Seattle');
+    expect(a2.state,null);
+    expect(a2.zip, null);
+  });
+
+  test('Slightly further with a simple object', () {
+    // TODO(alanknight): Tests that rely on what index rules are going to be
+    // at are very fragile. At least abstract it to something calculated.
+    var p1 = new Person()..name = 'Alice'..address = a1;
+    var s = new Serialization()
+        ..addRuleFor(p1).configureForMaps()
+        ..addRuleFor(a1).configureForMaps();
+    // TODO(alanknight): Need a better API for getting to flat state without
+    // actually writing.
+    var w = new Writer(s);
+    w.trace.addRoot(p1);
+    w.trace.traceAll();
+    w.flatten();
+    var flatPerson = w.states[3].first;
+    var primStates = w.states.first;
+    expect(primStates.isEmpty, true);
+    expect(flatPerson["name"], "Alice");
+    var ref = flatPerson["address"];
+    expect(ref is Reference, true);
+    expect(ref.ruleNumber, 4);
+    expect(ref.objectNumber, 0);
+    expect(w.states[4].first['street'], 'N 34th');
+  });
+
+  test('exclude fields', () {
+    var s = new Serialization()
+        ..addRuleFor(a1,
+            excludeFields: ['state', 'zip']).configureForMaps();
+    var extracted = states(a1, s).first;
+    expect(extracted.length, 2);
+    expect(extracted['street'], 'N 34th');
+    expect(extracted['city'], 'Seattle');
+    Reader reader = setUpReader(s, extracted);
+    Address a2 = readBackSimple(s, a1, reader);
+    expect(a2.state, null);
+    expect(a2.city, 'Seattle');
+  });
+
+  test('list', () {
+    var list = [5, 4, 3, 2, 1];
+    var s = new Serialization();
+    var extracted = states(list, s).first;
+    expect(extracted.length, 5);
+    for (var i = 0; i < 5; i++) {
+      expect(extracted[i], (5 - i));
+    }
+    Reader reader = setUpReader(s, extracted);
+    var list2 = readBackSimple(s, list, reader);
+    expect(list, list2);
+  });
+
+  test('different kinds of fields', () {
+    var x = new Various.Foo("d", "e");
+    x.a = "a";
+    x.b = "b";
+    x._c = "c";
+    var s = new Serialization()
+      ..addRuleFor(x,
+          constructor: "Foo",
+          constructorFields: ["d", "e"]);
+    var state = states(x, s).first;
+    expect(state.length, 4);
+    var expected = "abde";
+    for (var i in [0,1,2,3]) {
+      expect(state[i], expected[i]);
+    }
+    Reader reader = setUpReader(s, state);
+    Various y = readBackSimple(s, x, reader);
+    expect(x.a, y.a);
+    expect(x.b, y.b);
+    expect(x.d, y.d);
+    expect(x.e, y.e);
+    expect(y._c, 'default value');
+  });
+
+  test('Stream', () {
+    // This is an interesting case. The Stream doesn't expose its internal
+    // collection at all, and sets it in the constructor. So to get it we
+    // read a private field and then set that via the constructor. That works
+    // but should we have some kind of large red flag that you're using private
+    // state.
+    var stream = new Stream([3,4,5]);
+    expect((stream..next()).next(), 4);
+    expect(stream.position, 2);
+    var s = new Serialization()
+      ..addRuleFor(stream,
+          constructorFields: ['_collection']);
+    var state = states(stream, s).first;
+    // Define names for the variable offsets to make this more readable.
+    var _collection = 0, position = 1;
+    expect(state[_collection],[3,4,5]);
+    expect(state[position], 2);
+  });
+
+  test('date', () {
+    var date = new Date.now();
+    var s = new Serialization()
+        ..addRuleFor(date,
+            constructorFields : ["year", "month", "day", "hour", "minute",
+                                 "second", "millisecond", "isUtc"])
+            .configureForMaps();
+    var state = states(date, s).first;
+    expect(state["year"],date.year);
+    expect(state["isUtc"],date.isUtc);
+    expect(state["millisecond"], date.millisecond);
+  });
+
+  test('Iteration helpers', () {
+    var map = {"a" : 1, "b" : 2, "c" : 3};
+    var list = [1, 2, 3];
+    var set = new Set.from(list);
+    var m = keysAndValues(map);
+    var l = keysAndValues(list);
+    var s = keysAndValues(set);
+
+    m.forEach((key, value) {expect(key.charCodes[0], value + 96);});
+    l.forEach((key, value) {expect(key + 1, value);});
+    var index = 0;
+    var seen = new Set();
+    s.forEach((key, value) {
+      expect(key, index++);
+      expect(seen.contains(value), isFalse);
+      seen.add(value);
+    });
+    expect(seen.length, 3);
+
+    var i = 0;
+    m = values(map);
+    l = values(list);
+    s = values(set);
+    m.forEach((each) {expect(each, ++i);});
+    i = 0;
+    l.forEach((each) {expect(each, ++i);});
+    i = 0;
+    s.forEach((each) {expect(each, ++i);});
+    i = 0;
+
+    seen = new Set();
+    for (var each in m) {
+      expect(seen.contains(each), isFalse);
+      seen.add(each);
+    }
+    expect(seen.length, 3);
+    i = 0;
+    for (var each in l) {
+      expect(each, ++i);
+    }
+  });
+
+  Node n1 = new Node("1"), n2 = new Node("2"), n3 = new Node("3");
+  n1.children = [n2, n3];
+  n2.parent = n1;
+  n3.parent = n1;
+
+  test('Trace a cyclical structure', () {
+    var s = new Serialization();
+    var trace = new Trace(new Writer(s));
+    trace.writer.trace = trace;
+    trace.trace(n1);
+    var all = trace.writer.references.keys;
+    expect(all.length, 4);
+    expect(all.contains(n1), isTrue);
+    expect(all.contains(n2), isTrue);
+    expect(all.contains(n3), isTrue);
+    expect(all.contains(n1.children), isTrue);
+  });
+
+  test('Flatten references in a cyclical structure', () {
+    var s = new Serialization();
+    var w = new Writer(s);
+    w.trace = new Trace(w);
+    w.write(n1);
+    expect(w.states.length, 4); // prims, lists, essential lists, basic
+    var children = 0, name = 1, parent = 2;
+    List rootNode = w.states[3].filter((x) => x[name] == "1");
+    rootNode = rootNode.first;
+    expect(rootNode[parent], isNull);
+    var list = w.states[1].first;
+    expect(w.stateForReference(rootNode[children]), list);
+    var parentNode = w.stateForReference(list[0])[parent];
+    expect(w.stateForReference(parentNode), rootNode);
+  });
+
+  test('round-trip', () {
+    runRoundTripTest(nodeSerializerReflective);
+  });
+
+  test('round-trip hard-coded', () {
+    runRoundTripTest(nodeSerializerNonReflective);
+  });
+
+  test('round-trip with essential parent', () {
+    runRoundTripTest(nodeSerializerWithEssentialParent);
+  });
+
+  test('round-trip, flat format', () {
+    runRoundTripTestFlat(nodeSerializerReflective);
+  });
+
+  test('round-trip using Maps', () {
+    runRoundTripTest(nodeSerializerUsingMaps);
+  });
+
+  test('eating your own tail', () {
+    // Create a meta-serializer, that serializes serializations, then
+    // use it to serialize a basic serialization, then run a test on the
+    // the result.
+    var s = new Serialization()
+      ..addRuleFor(new Node(''), constructorFields: ['name'])
+      ..selfDescribing = false;
+    var meta = metaSerialization();
+    var serialized = meta.write(s);
+    var s2 = new Reader(meta)
+        .readOne(serialized, {"Node" : reflect(new Node('')).type});
+    runRoundTripTest((x) => s2);
+  });
+
+  test("Verify we're not serializing lists twice if they're essential", () {
+    Node n1 = new Node("1"), n2 = new Node("2"), n3 = new Node("3");
+    n1.children = [n2, n3];
+    n2.parent = n1;
+    n3.parent = n1;
+    var s = new Serialization()
+      ..addRuleFor(n1, constructorFields: ["name"]).
+          specialTreatmentFor("children", (parent, child) =>
+              parent.reflectee.children = child);
+    var w = new Writer(s);
+    w.write(n1);
+    expect(w.rules[2] is ListRuleEssential, isTrue);
+    expect(w.rules[1] is ListRule, isTrue);
+    expect(w.states[1].length, 0);
+    expect(w.states[2].length, 1);
+    s = new Serialization()
+      ..addRuleFor(n1, constructorFields: ["name"]);
+    w = new Writer(s);
+    w.write(n1);
+    expect(w.states[1].length, 1);
+    expect(w.states[2].length, 0);
+  });
+
+  test('Identity of equal objects preserved', () {
+    Node n1 = new NodeEqualByName("foo"),
+         n2 = new NodeEqualByName("foo"),
+         n3 = new NodeEqualByName("3");
+    n1.children = [n2, n3];
+    n2.parent = n1;
+    n3.parent = n1;
+    var s = new Serialization()
+      ..selfDescribing = false
+      ..addRuleFor(n1, constructorFields: ["name"]);
+    var w = new Writer(s);
+    var r = new Reader(s);
+    var m1 = r.read(w.write(n1)).first;
+    var m2 = m1.children.first;
+    var m3 = m1.children.last;
+    expect(m1, m2);
+    expect(identical(m1, m2), isFalse);
+    expect(m1 == m3, isFalse);
+    expect(identical(m2.parent, m3.parent), isTrue);
+  });
+
+}
+
+/******************************************************************************
+ * The end of the tests and the beginning of various helper functions to make
+ * it easier to write the repetitive sections.
+ ******************************************************************************/
+
+/** Create a Serialization for serializing Serializations. */
+Serialization metaSerialization() {
+  // Make some bogus rule instances so we have something to feed rule creation
+  // and get their types. If only we had class literals implemented...
+  var closureRule = new ClosureToMapRule.stub([].runtimeType);
+  var basicRule = new BasicRule(reflect(null).type, '', [], [], []);
+
+  var meta = new Serialization()
+    ..selfDescribing = false
+    ..addRuleFor(new ListRule())
+    ..addRuleFor(new PrimitiveRule())
+    // TODO(alanknight): Handle the ClosureToMapRule as well.
+    // Note that we're passing in a constant for one of the fields.
+    ..addRuleFor(basicRule,
+        constructorFields: ['typeWrapped',
+          'constructorName',
+          'constructorFields', 'regularFields', []],
+        fields: [])
+     ..addRuleFor(new Serialization()).specialTreatmentFor('rules',
+         (InstanceMirror s, List rules) {
+             rules.forEach((x) => s.reflectee.addRule(x));
+         })
+    ..addRule(new ClassMirrorRule());
+  return meta;
+}
+
+/**
+ * Read back a simple object, assumed to be the only one of its class in the
+ * reader.
+ */
+readBackSimple(Serialization s, object, Reader reader) {
+  var rule = s.rulesFor(object)[0];
+  reader.inflateForRule(rule);
+  var list2 = reader.allObjectsForRule(rule)[0];
+  return list2;
+}
+
+/**
+ * Set up a basic reader with some fake data. Hard-codes the assumption
+ * of how many rules there are.
+ */
+Reader setUpReader(aSerialization, sampleData) {
+  var reader = new Reader(aSerialization);
+  // We're not sure which rule needs the sample data, so put it everywhere
+  // and trust that the extra will just be ignored.
+  reader.data = [[sampleData], [sampleData], [sampleData], [sampleData]];
+  return reader;
+}
+
+/** Return a serialization for Node objects, using a reflective rule. */
+Serialization nodeSerializerReflective(Node n) {
+  return new Serialization()
+    ..addRuleFor(n, constructorFields: ["name"])
+    ..externalObjects['Node'] = reflect(new Node('')).type;
+}
+
+/**
+ * Return a serialization for Node objects but using Maps for the internal
+ * representation rather than lists.
+ */
+Serialization nodeSerializerUsingMaps(Node n) {
+  return new Serialization()
+    ..addRuleFor(n, constructorFields: ["name"]).configureForMaps()
+    ..externalObjects['Node'] = reflect(new Node('')).type;
+}
+
+/**
+ * Return a serialization for Node objects where the "parent" instance
+ * variable is considered essential state.
+ */
+Serialization nodeSerializerWithEssentialParent(Node n) {
+  var s = new Serialization()
+    ..addRuleFor(
+        n,
+        constructor: "parentEssential",
+        constructorFields: ["parent"])
+    ..externalObjects['Node'] = reflect(new Node('')).type
+    ..selfDescribing = false;
+
+  // Force the node rule to be first, in order to make a cycle which would
+  // not cause a problem if we handled the list first, because the list
+  // considers all of its state non-essential, thus breaking the cycle.
+  s.rules = append([s.rules.removeLast()], s.rules);
+  keysAndValues(s.rules).forEach((index, rule) => rule.number = index);
+  return s;
+}
+
+/** Return a serialization for Node objects using a ClosureToMapRule. */
+Serialization nodeSerializerNonReflective(Node n) {
+  var rule = new ClosureToMapRule(
+      n.runtimeType,
+      (o) => {"name" : o.name, "children" : o.children, "parent" : o.parent},
+      (map) => new Node(map["name"]),
+      (map, object) { object

[Jennifer Messerly, 2012/11/20 01:20:47]

personally I'd put "object" on next line, and only indent the block by 2:
http://www.dartlang.org/articles/style-guide/#do-indent-blocks-with-two-spaces

[Alan Knight, 2012/11/20 12:17:54]

Done.

+          ..children = map["children"]
+          ..parent = map["parent"];
+      });
+  return new Serialization()
+    ..selfDescribing = false
+    ..addRule(rule);
+}
+
+/**
+ * Run a round-trip test on a simple tree of nodes, using a serialization
+ * that's returned by the [serializerSetup] function.
+ */
+runRoundTripTest(Function serializerSetUp) {
+  Node n1 = new Node("1"), n2 = new Node("2"), n3 = new Node("3");
+  n1.children = [n2, n3];
+  n2.parent = n1;
+  n3.parent = n1;
+  var s = serializerSetUp(n1);
+  var output = s.write(n2);
+  var s2 = serializerSetUp(n1);
+  var reader = new Reader(s2);
+  var m2 = reader.readOne(output);
+  var m1 = m2.parent;
+  expect(m1 is Node, isTrue);
+  var children = m1.children;
+  expect(m1.name,"1");
+  var m3 = m1.children.last;
+  expect(m2.name, "2");
+  expect(m3.name, "3");
+  expect(m2.parent, m1);
+  expect(m3.parent, m1);
+  expect(m1.parent, isNull);
+}
+
+/**
+ * Run a round-trip test on a simple of nodes, but using the flat format
+ * rather than the maps.
+ */
+runRoundTripTestFlat(serializerSetUp) {
+  Node n1 = new Node("1"), n2 = new Node("2"), n3 = new Node("3");
+  n1.children = [n2, n3];
+  n2.parent = n1;
+  n3.parent = n1;
+  var s = serializerSetUp(n1);
+  var output = s.writeFlat(n2);
+  var s2 = serializerSetUp(n1);
+  var reader = new Reader(s2);
+  var m2 = reader.readFlat(output).first;
+  var m1 = m2.parent;
+  expect(m1 is Node, isTrue);
+  var children = m1.children;
+  expect(m1.name,"1");
+  var m3 = m1.children.last;
+  expect(m2.name, "2");
+  expect(m3.name, "3");
+  expect(m2.parent, m1);
+  expect(m3.parent, m1);
+  expect(m1.parent, isNull);
+}
+
+/** Extract the state from [object] using the rules in [s] and return it. */
+states(Object object, Serialization s) {
+  var rules = s.rulesFor(object);
+  return rules.map( (x) => x.extractState(object, doNothing));

[Jennifer Messerly, 2012/11/20 01:20:47]

looks like an extra space here

[Alan Knight, 2012/11/20 12:17:54]

Done.

+}