Improve disconnection and reconnection (#148)

***NO_CI***

Author: networkfusion

.runsettings

@@ -25,6 +25,9 @@
     <RestoreLockedMode Condition="'$(TF_BUILD)' == 'True' or '$(ContinuousIntegrationBuild)' == 'True'">true</RestoreLockedMode>
   </PropertyGroup>
   <Import Project="$(NanoFrameworkProjectSystemPath)NFProjectSystem.props" Condition="Exists('$(NanoFrameworkProjectSystemPath)NFProjectSystem.props')" />
+  <PropertyGroup>
+    <RunSettingsFilePath>$(MSBuildProjectDirectory)\nano.runsettings</RunSettingsFilePath>
+  </PropertyGroup>
   <ItemGroup>
     <Compile Include="ShadowTests.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />

Tests/Aws.IoTCore.Devices.UnitTests.nfproj

@@ -49,6 +49,8 @@ steps:
 - template: azure-pipelines-templates/class-lib-build.yml@templates
   parameters:
     sonarCloudProject: 'nanoFramework.Aws.IoTCore.Devices'
+    runUnitTests: true
+    unitTestRunsettings: '$(System.DefaultWorkingDirectory)/Tests/nano.runsettings'
 
 # step from template @ nf-tools repo
 # report error

azure-pipelines.yml

@@ -51,7 +51,7 @@ public enum QoSLevel
         private readonly X509Certificate2 _clientCert; //Combined ClientRsaSha256Crt and ClientRsaKey
         private readonly X509Certificate _awsRootCACert;
 
-        private M2Mqtt.MqttClient _mqttc;
+        private M2Mqtt.MqttClient _mqttc = null;
         private readonly ConnectorState _mqttBrokerStatus = new ConnectorState();
         private readonly ArrayList _waitForConfirmation = new ArrayList();
         private readonly object _lock = new object();
@@ -243,18 +243,22 @@ private void TimerCallbackReconnect(object state)
         /// </summary>
         public void Close()
         {
-            if (_mqttc.IsConnected)
+            if (_mqttc != null)
             {
-                _mqttc.Unsubscribe(new[] {
+                if (_mqttc.IsConnected)
+                {
+                    _mqttc.Unsubscribe(new[] {
                     $"{_deviceMessageTopic}/#",
                     $"{ _shadowTopic }/#",
                     });
+                }
                 _mqttc.Disconnect();
+                _mqttc.Close();
                 // Make sure all get disconnected, cleared (TODO: 1 second arbitrary value specified)
                 Thread.Sleep(1000);
             }
 
-            _timerTokenRenew.Dispose();
+            _timerTokenRenew?.Dispose();
         }
 
         /// <summary>

nanoFramework.Aws.IoTCore.Devices/MqttConnectionClient.cs

@@ -46,9 +46,6 @@
   <ItemGroup>
     <None Include="packages.config" />
   </ItemGroup>
-  <ItemGroup>
-    <None Include="packages.lock.json" />
-  </ItemGroup>
   <ItemGroup>
     <Reference Include="mscorlib, Version=1.14.3.0, Culture=neutral, PublicKeyToken=c07d481e9758c731">
       <HintPath>..\packages\nanoFramework.CoreLibrary.1.14.2\lib\mscorlib.dll</HintPath>
@@ -92,7 +89,7 @@
     </Reference>
   </ItemGroup>
   <ItemGroup>
-    <None Include="packages.config" />
+    <Content Include="packages.lock.json" />
   </ItemGroup>
   <Import Project="$(NanoFrameworkProjectSystemPath)NFProjectSystem.CSharp.targets" Condition="Exists('$(NanoFrameworkProjectSystemPath)NFProjectSystem.CSharp.targets')" />
   <ProjectExtensions>

nanoFramework.Aws.IoTCore.Devices/nanoFramework.Aws.IoTCore.Devices.nfproj

@@ -2,7 +2,7 @@
   "$schema": "https://raw.githubusercontent.com/dotnet/Nerdbank.GitVersioning/master/src/NerdBank.GitVersioning/version.schema.json",
   "version": "1.1",
   "assemblyVersion": {
-    "precision": "minor"
+    "precision": "revision"
   },
   "semVer1NumericIdentifierPadding": 3,
   "nuGetPackageVersion": {