Ignore empty XMPP messages

Emulsion.Tests/Xmpp/SharpXmppHelper.fs

@@ -54,3 +54,18 @@ let ``isHistoricalMessage returns false for an ordinary message``() =
 let ``isHistoricalMessage returns true for a message with delay``() =
     let message = XmppMessageFactory.create(delayDate = "2010-01-01")
     Assert.True(SharpXmppHelper.isHistoricalMessage message)
+
+[<Fact>]
+let ``Message without body is considered as empty``(): unit =
+    let message = XmppMessageFactory.create()
+    Assert.True(SharpXmppHelper.isEmptyMessage message)
+
+[<Fact>]
+let ``Message consisting of whitespace is considered as empty``(): unit =
+    let message = XmppMessageFactory.create(text = "     \t ")
+    Assert.True(SharpXmppHelper.isEmptyMessage message)
+
+[<Fact>]
+let ``Message with text is not considered as empty``(): unit =
+    let message = XmppMessageFactory.create(text = "     t ")
+    Assert.False(SharpXmppHelper.isEmptyMessage message)

Emulsion/Xmpp/SharpXmppHelper.fs

@@ -1,5 +1,6 @@
 module Emulsion.Xmpp.SharpXmppHelper
 
+open System
 open System.Xml.Linq
 
 open SharpXMPP
@@ -61,6 +62,9 @@ let isHistoricalMessage (message : XMPPMessage) : bool =
         |> Seq.isEmpty
     )
 
+let isEmptyMessage(message: XMPPMessage): bool =
+    String.IsNullOrWhiteSpace message.Text
+
 let parseMessage (message: XMPPMessage): Message =
     let nickname =
         getAttributeValue message From

Emulsion/Xmpp/XmppClient.fs

@@ -23,6 +23,7 @@ let private signedInHandler (logger: ILogger) (settings: XmppSettings) (client:
 let private shouldSkipMessage settings message =
     SharpXmppHelper.isOwnMessage (settings.Nickname) message
         || SharpXmppHelper.isHistoricalMessage message
+        || SharpXmppHelper.isEmptyMessage message
 
 let private messageHandler (logger: ILogger) settings onMessage = XmppConnection.MessageHandler(fun _ element ->
     logger.Verbose("Incoming XMPP message: {Message}", element)