Fix Packet size mismatch! error on collection drop

.gitignore

@@ -46,3 +46,4 @@ examples/bench-mongodb/bench-mongodb
 examples/bench-urlrouter/bench-urlrouter
 *.exe
 
+tests/mongodb/collection/tests

mongodb/vibe/db/mongo/connection.d

@@ -714,7 +714,7 @@ final class MongoConnection {
 	{
 		import std.traits;
 
-		auto bytes_read = m_bytesRead;
+		auto packet_start_index = m_bytesRead;
 		int msglen = recvInt();
 		int resid = recvInt();
 		int respto = recvInt();
@@ -731,7 +731,7 @@ final class MongoConnection {
 			sectionLength -= uint.sizeof; // CRC present
 
 		bool gotSec0;
-		while (m_bytesRead - bytes_read < sectionLength) {
+		while (m_bytesRead - packet_start_index < msglen) {
 			// TODO: directly deserialize from the wire
 			static if (!dupBson) {
 				ubyte[256] buf = void;
@@ -783,9 +783,9 @@ final class MongoConnection {
 			logDiagnostic("recvData: crc=%s (discarded)", crc);
 		}
 
-		assert(bytes_read + msglen == m_bytesRead,
+		assert(packet_start_index + msglen == m_bytesRead,
 			format!"Packet size mismatch! Expected %s bytes, but read %s."(
-				msglen, m_bytesRead - bytes_read));
+				msglen, m_bytesRead - packet_start_index));
 
 		return resid;
 	}

tests/mongodb/collection/dub.json

@@ -0,0 +1,7 @@
+{
+    "name": "tests",
+    "description": "High level MongoDB collection tests for vibe.d",
+    "dependencies": {
+        "vibe-d:mongodb": {"path": "../../../"}
+    }
+}

tests/mongodb/collection/source/app.d

@@ -0,0 +1,39 @@
+/// Requires mongo service running on localhost with default port
+/// Uses test database
+
+module app;
+
+import vibe.core.core;
+import vibe.core.log;
+import vibe.data.bson;
+import vibe.db.mongo.mongo;
+
+import std.algorithm : all, canFind, equal, map, sort;
+import std.conv : to;
+import std.encoding : sanitize;
+import std.exception : assertThrown;
+
+
+void runTest(ushort port)
+{
+	MongoClient client = connectMongoDB("127.0.0.1", port);
+
+	/// Drop a collection
+	auto chunks = client.getCollection("test.fs.chunks");
+	chunks.drop;
+}
+
+int main(string[] args)
+{
+	int ret = 0;
+	ushort port = args.length > 1
+		? args[1].to!ushort
+		: MongoClientSettings.defaultPort;
+	runTask(() nothrow {
+		try runTest(port);
+		catch (Exception e) assert(false, e.toString());
+		finally exitEventLoop(true);
+	});
+	runEventLoop();
+	return ret;
+}