collection('...').document() should not save a document

[suztomo]

With current implementation, the following test code fails:

    final reference1 = firestore.collection('users').document();
    final reference2 = firestore.collection('users').document();

    await reference1.setData({
      'someField': 'someValue',
    });

    QuerySnapshot querySnapshot = await firestore.collection('users').getDocuments();
    // Only reference1 is saved
    expect(querySnapshot.documents, hasLength(1));
    expect(querySnapshot.documents.first['someField'], 'someValue');

It fails because as of now cloud_firestore_mocks does not distinguish saved and unsaved documents.

I suspect code below should be updated to accommodate this.

  @override
  DocumentReference document([String path]) {
    if (path == null) {
      path = _generateAutoId();
    }

    return MockDocumentReference(path, getSubpath(root, path), root,
        getSubpath(snapshotStreamControllerRoot, path));
  }

getSubpath(root, path) creates a document to the root.

[suztomo]

Initial Attempt failed

Initial attempt that avoids modifying rootParent until updateData and setData failed.
suztomo@3ed76fe#diff-855d1299f8d5526ef0aacc2ddf24af06R28

This attempt fails to record subcollection whose parent is not saved.
cloud_firestore_mocks internally maintains documents as a tree using Map. When parent is not saved, getting collection reference creates a new map which does not have the subcolleciton.

This issue requires to save whether a document is stored in the instance or not. Maybe MockFirestoreInstance remembers all saved document location such as /users/t1gVCkBrgMU9LjFRnrtu1FFjlir1/persons/FkHWNY0ISMz9Zia0mF0q and MockDocumentReference and MockCollectionReference remembers MockFirestoreInstance.

[suztomo]

Note. In real Firestore, creating a non-top-level document does not create its parent document. For example, creating users/abc/friends/{documentId} does not create a document at users/abc.

    final firestore = Firestore.instance;
    await firestore.collection('dummy').document('abc')
    .collection('friends').document().setData(
      <String, dynamic>{
        'name': 'Tomo',
      }
    );

    final abcSaved = await firestore.collection('dummy').document('abc').get();
    if (abcSaved.exists) { // This is false.
      print('$abcSaved');
    }