Add ImportHistory class and RecordStorage class.

chrome/test/data/file_manager/unit_tests/import_history_unittest.js

Index: chrome/test/data/file_manager/unit_tests/import_history_unittest.js
diff --git a/chrome/test/data/file_manager/unit_tests/import_history_unittest.js b/chrome/test/data/file_manager/unit_tests/import_history_unittest.js
new file mode 100644
index 0000000000000000000000000000000000000000..b0fece8ee9984c2e014f0fec1fc97d7df8572e96
--- /dev/null
+++ b/chrome/test/data/file_manager/unit_tests/import_history_unittest.js
@@ -0,0 +1,161 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+'use strict';
+
+/** @const {string} */
+var GOOGLE_DRIVE = 'Google Drive';
+
+/**
+ * Space Cloud: Your source for interstellar cloud storage.
+ * @const {string}
+ */
+var SPACE_CLOUD = 'Space Cloud';
+
+/** @type {!TestFileSystem|undefined} */
+var testFileSystem;
+
+/** @type {!MockFileEntry|undefined} */
+var testFileEntry;
+
+/** @type {!RecordStorage|undefined} */
+var storage;
+
+/** @type {!Promise.<ImportHistory>|undefined} */
+var historyLoader;
+
+// Set up the test components.
+function setUp() {
+  testFileSystem = new TestFileSystem('abc-123');
+  testFileEntry = new MockFileEntry(
+      testFileSystem,
+      'hey/there', {
+        size: 1234,
+        modificationTime: 'Thursday, very late'

[mtomasz, 2014/10/29 01:10:40]

nit: Can we use a Date object?

[Steve McKay, 2014/10/29 16:57:21]

Done (in a const), but the type is still string.

+      });
+
+  storage = new TestRecordStorage();
+  historyLoader = ImportHistory.load(storage);
+}
+
+/**
+ * In-memory test implementation of {@code RecordStorage}.
+ *
+ * @constructor
+ * @implements {RecordStorage}
+ */
+var TestRecordStorage = function() {
+
+  // Pre-populate the store with some "previously written" data <wink>.
+  /** @private {!Array.<!Array.<string>>} */
+  this.records_ = [
+    ['Thursday, very late_1234', GOOGLE_DRIVE],
+    ['99999_99999', SPACE_CLOUD]
+  ];
+
+  /**
+   * @override
+   * @this {TestRecordStorage}
+   */
+  this.readAll = function() {
+    return Promise.resolve(this.records_);
+  };
+
+  /**
+   * @override
+   * @this {TestRecordStorage}
+   */
+  this.write = function(record) {
+    this.records_.push(record);
+    return Promise.resolve();
+  };
+};
+
+/**
+ * @return {!Promise.<RecordStorage>}
+ */
+function createRealStorage() {
+  return new Promise(
+      function(resolve, reject) {
+        var onFilesystemReady = function(fileSystem) {
+          fileSystem.root.getFile(
+              'test.data',
+              {
+                create: true,
+                exclusive: false
+              },
+              function(fileEntry) {
+                resolve(new FileEntryRecordStorage(fileEntry));
+              },
+              reject);
+        };
+
+        window.webkitRequestFileSystem(
+            TEMPORARY,
+            1024 * 1024,
+            onFilesystemReady,
+            reject);
+      });
+}
+
+function testRecordStorage(callback) {

[mtomasz, 2014/10/29 01:10:40]

nit: Shall we add jsdoc to these functions?

[Steve McKay, 2014/10/29 16:57:21]

I've always been of the opinion that tests should be small enough and well named
enough that jsdoc is not needed. The big win in doing it this way is that when a
test fails, the name alone provides a clear description of what the test was
supposed to be guaranteeing...no need to lookup the comment in source.

NOTE: Updated test method names to make it more explanatory.

+  createRealStorage()
+      .then(
+          function(storage) {
+            storage.write(['abc', '123']).then(
+                function() {
+                  storage.readAll().then(
+                      function(records) {
+                        callback(/* error */ records.length != 1);
+                      },
+                      callback);
+                });
+            },
+            callback)
+      .catch(handleError_.bind(callback));
+}
+
+function testHistoryNotImported(callback) {
+  // TestRecordWriter is pre-configured with a Space Cloud entry
+  // but not for this file.
+  historyLoader.then(
+      function(testHistory) {
+        testHistory.wasImported(testFileEntry, SPACE_CLOUD).then(
+          function(result) {
+            callback(/* error */ result);
+          });
+      })
+  .catch(handleError_.bind(callback));
+}
+
+function testHistoryLoadsStoredRecords(callback) {
+  // TestRecordWriter is pre-configured with this entry.
+  historyLoader.then(
+      function(testHistory) {
+        testHistory.wasImported(testFileEntry, GOOGLE_DRIVE).then(
+          function(result) {
+            callback(/* error */ !result);
+          });
+      })
+  .catch(handleError_.bind(callback));
+}
+
+function testHistoryUpdates(callback) {
+  historyLoader.then(
+      function(testHistory) {
+        testHistory.markImported(testFileEntry, SPACE_CLOUD).then(
+            function() {
+              testHistory.wasImported(testFileEntry, SPACE_CLOUD).then(
+                  function(result) {
+                    callback(/* error */ !result);
+                  });
+            });
+      })
+  .catch(handleError_.bind(callback));
+}
+

[mtomasz, 2014/10/29 01:10:40]

nit: \n\n -> \n

[Steve McKay, 2014/10/29 16:57:21]

Done.

+
+function handleError_(callback, error) {

[mtomasz, 2014/10/29 01:10:40]

nit: Private in what scope? Maybe no need for _ at the end?
nit: jsdoc missing
nit: ; at the end redundant

[Steve McKay, 2014/10/29 16:57:21]

Hmmm. Good point. It would be file scoped if such a thing existed. Nuked
@private.

+  console.error(error.stack || error);
+  callback(/* error */ true);
+};