Add DocumentReference#getCollections

https://cloud.google.com/nodejs/docs/reference/firestore/0.15.x/DocumentReference#getCollections

Author: ilearnio

src/firestore-document.js

@@ -165,6 +165,24 @@ MockFirestoreDocument.prototype.delete = function (callback) {
   });
 };
 
+/**
+ * Fetches the subcollections that are direct children of the document.
+ * @see https://cloud.google.com/nodejs/docs/reference/firestore/0.15.x/DocumentReference#getCollections
+ */
+MockFirestoreDocument.prototype.getCollections = function () {
+  var err = this._nextErr('getCollections');
+  var self = this;
+  return new Promise(function (resolve, reject) {
+    self._defer('getCollections', _.toArray(arguments), function () {
+      if (err === null) {
+        resolve(_.toArray(this.children));
+      } else {
+        reject(err);
+      }
+    });
+  });
+};
+
 MockFirestoreDocument.prototype._hasChild = function (key) {
   return _.isObject(this.data) && _.has(this.data, key);
 };

test/unit/firestore-document.js

@@ -349,4 +349,56 @@ describe('MockFirestoreDocument', function () {
       expect(result).to.eventually.equal(null);
     });
   });
+
+  describe('#getCollections', function () {
+    beforeEach(function () {
+      db.doc('doc/subcol/subcol-doc').set({ foo: 'bar' });
+      db.doc('doc/subcol2/subcol-doc').set({ foo: 'bar' });
+      db.doc('doc/subcol/subcol-doc/deep-col/deep-doc').set({ foo: 'bar' });
+      db.doc('doc/subcol/subcol-doc/deep-col2/deep-doc').set({ foo: 'bar' });
+      db.flush();
+    });
+    afterEach(function () {
+      db.doc('doc/subcol/subcol-doc').delete();
+      db.doc('doc/subcol2/subcol-doc').delete();
+      db.doc('doc/subcol/subcol-doc/deep-col/deep-doc').delete();
+      db.doc('doc/subcol/subcol-doc/deep-col2/deep-doc').delete();
+      db.flush();
+    });
+
+    context('when present', function () {
+      it('returns collections of document', function (done) {
+        db.doc('doc').getCollections().then(function (colRefs) {
+          expect(colRefs).to.be.an('array');
+          expect(colRefs).to.have.length(2);
+          expect(colRefs[0].path).to.equal('doc/subcol');
+          expect(colRefs[1].path).to.equal('doc/subcol2');
+          done();
+        });
+        db.flush();
+      });
+
+      it('returns deeply nested collections of document', function (done) {
+        db.doc('doc/subcol/subcol-doc').getCollections().then(function (colRefs) {
+          expect(colRefs).to.be.an('array');
+          expect(colRefs).to.have.length(2);
+          expect(colRefs[0].path).to.equal('doc/subcol/subcol-doc/deep-col');
+          expect(colRefs[1].path).to.equal('doc/subcol/subcol-doc/deep-col2');
+          done();
+        });
+        db.flush();
+      });
+    });
+
+    context('when not present', function () {
+      it('returns deeply nested collections of document', function (done) {
+        db.doc('not-existing').getCollections().then(function (colRefs) {
+          expect(colRefs).to.be.an('array');
+          expect(colRefs).to.have.length(0);
+          done();
+        });
+        db.flush();
+      });
+    });
+  });
 });