1 files changed, 45 insertions, 0 deletions
diff --git a/jstests/sharding/shard_existing.js b/jstests/sharding/shard_existing.js
new file mode 100644
index 00000000000..5430b5577fc
--- /dev/null
+++ b/jstests/sharding/shard_existing.js
@@ -0,0 +1,45 @@
+/*
+ * @tags: [
+ *   requires_fcv_51,
+ * ]
+ */
+
+(function() {
+'use strict';
+
+load("jstests/sharding/libs/find_chunks_util.js");
+
+var s = new ShardingTest({name: "shard_existing", shards: 2, mongos: 1, other: {chunkSize: 1}});
+var db = s.getDB("test");
+
+var stringSize = 10000;
+var numDocs = 2000;
+
+// we want a lot of data, so lets make a string to cheat :)
+var bigString = new Array(stringSize).toString();
+var docSize = Object.bsonsize({_id: numDocs, s: bigString});
+var totalSize = docSize * numDocs;
+print("NumDocs: " + numDocs + " DocSize: " + docSize + " TotalSize: " + totalSize);
+
+var bulk = db.data.initializeUnorderedBulkOp();
+for (var i = 0; i < numDocs; i++) {
+    bulk.insert({_id: i, s: bigString});
+}
+assert.commandWorked(bulk.execute());
+
+var avgObjSize = db.data.stats().avgObjSize;
+var dataSize = db.data.stats().size;
+assert.lte(totalSize, dataSize);
+
+s.adminCommand({enablesharding: "test"});
+s.ensurePrimaryShard('test', s.shard1.shardName);
+var res = s.adminCommand({shardcollection: "test.data", key: {_id: 1}});
+printjson(res);
+
+// number of chunks should be approx equal to the total data size / chunk size
+var numChunks = findChunksUtil.findChunksByNs(s.config, 'test.data').itcount();
+var guess = Math.ceil(dataSize / (1024 * 1024 + avgObjSize));
+assert.lte(Math.abs(numChunks - guess), 2, "not right number of chunks");
+
+s.stop();
+})();