SERVER-8046 Cleanup Element::writeArrayTo and add a test for the new implementation

3 files changed, 21 insertions, 8 deletions

diff --git a/src/mongo/bson/mutable/document.cpp b/src/mongo/bson/mutable/document.cpp
index f8cee4b8913..27c1411240d 100644
--- a/src/mongo/bson/mutable/document.cpp
+++ b/src/mongo/bson/mutable/document.cpp
@@ -1459,7 +1459,7 @@ namespace mutablebson {
         const Document::Impl& impl = getDocument().getImpl();
         const ElementRep& thisRep = impl.getElementRep(_repIdx);
         verify(impl.getType(thisRep) == mongo::Array);
-        return writeElement(builder);
+        return writeChildren(builder);
     }
 
     Status Element::setValueDouble(const double value) {
diff --git a/src/mongo/bson/mutable/element.cpp b/src/mongo/bson/mutable/element.cpp
index 79de5b073ec..746c4c43dbe 100644
--- a/src/mongo/bson/mutable/element.cpp
+++ b/src/mongo/bson/mutable/element.cpp
@@ -158,10 +158,12 @@ namespace mutablebson {
             BSONObj obj = builder.obj();
             return obj.firstElement().toString();
         } else if (isType(mongo::Array)) {
-            BSONArrayBuilder builder;
-            writeArrayTo(&builder);
-            BSONArray arr = builder.arr();
-            return arr.firstElement().toString();
+            BSONObjBuilder builder;
+            BSONArrayBuilder arrayBuilder(builder.subarrayStart(getFieldName()));
+            writeArrayTo(&arrayBuilder);
+            arrayBuilder.done();
+            BSONObj obj = builder.obj();
+            return obj.firstElement().toString();
         } else {
             return "corrupted element";
         }
diff --git a/src/mongo/bson/mutable/mutable_bson_test.cpp b/src/mongo/bson/mutable/mutable_bson_test.cpp
index 57a8eeb64ce..af8f3224fc1 100644
--- a/src/mongo/bson/mutable/mutable_bson_test.cpp
+++ b/src/mongo/bson/mutable/mutable_bson_test.cpp
@@ -1407,14 +1407,25 @@ namespace {
     TEST(Document, toStringEphemeralObject) {
         mmb::Document doc;
         mmb::Element e = doc.makeElementObject("foo");
-        doc.root().pushBack(e);
-        e.appendDouble("d", 1.0);
-        e.appendString("s", "str");
+        ASSERT_OK(doc.root().pushBack(e));
+        ASSERT_OK(e.appendDouble("d", 1.0));
+        ASSERT_OK(e.appendString("s", "str"));
         ASSERT_EQUALS(
             mongo::fromjson("{ foo: { d : 1.0, s : 'str' } }").firstElement().toString(),
             e.toString());
     }
 
+    TEST(Document, toStringEphemeralArray) {
+        mmb::Document doc;
+        mmb::Element e = doc.makeElementArray("foo");
+        ASSERT_OK(doc.root().pushBack(e));
+        ASSERT_OK(e.appendDouble(mongo::StringData(), 1.0));
+        ASSERT_OK(e.appendString(mongo::StringData(), "str"));
+        ASSERT_EQUALS(
+            mongo::fromjson("{ foo: [ 1.0, 'str' ] }").firstElement().toString(),
+            e.toString());
+    }
+
     TEST(Document, ElementCloningToDifferentDocument) {
 
         const char initial[] = "{ a : 1, b : [ 1, 2, 3 ], c : { 'c' : 'c' }, d : [ 4, 5, 6 ] }";