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Unit testing of Realm in Xamarin iOS

Xamarin iOS native app. I have to write unit test for Realm api. It is the layer with ability to filter data. It can contain complicated Linq queries, so testing is necessary.
For instance, method:
Task<List<T>> Get(int count, int type, int? id);
Creating NUnit test I need to get Realm object:
var realm = Realm.GetInstance(new InMemoryConfiguration("test"));
but getting an exception:
System.TypeInitializationException : The type initializer for 'Realms.SharedRealmHandle' threw an exception.
----> System.DllNotFoundException : realm-wrappers assembly:<unknown assembly> type:<unknown type> member:(null)
at Realms.InMemoryConfiguration.CreateRealm (Realms.Schema.RealmSchema schema) [0x0003e] in C:\jenkins\workspace\realm_realm-dotnet_PR\Realm\Realm\Configurations\InMemoryConfiguration.cs:62
at Realms.Realm.GetInstance (Realms.RealmConfigurationBase config, Realms.Schema.RealmSchema schema) [0x0003c] in C:\jenkins\workspace\realm_realm-dotnet_PR\Realm\Realm\Realm.cs:136
at Realms.Realm.GetInstance (Realms.RealmConfigurationBase config) [0x00000] in C:\jenkins\workspace\realm_realm-dotnet_PR\Realm\Realm\Realm.cs:81
at UnitTestREALM.TransactionsRealmApiTest.RealmApi () [0x00001] in /Users/user/Projects/myApp/UnitTestREALM/TransactionsRealmApiTest.cs:26
at (wrapper managed-to-native) System.Reflection.RuntimeMethodInfo.InternalInvoke(System.Reflection.RuntimeMethodInfo,object,object[],System.Exception&)
at System.Reflection.RuntimeMethodInfo.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x0006a] in /Users/builder/jenkins/workspace/build-package-osx-mono/2020-02/external/bockbuild/builds/mono-x64/mcs/class/corlib/System.Reflection/RuntimeMethodInfo.cs:395
--DllNotFoundException
at (wrapper managed-to-native) Realms.SynchronizationContextEventLoopSignal.install_eventloop_callbacks(Realms.SynchronizationContextEventLoopSignal/get_eventloop,Realms.SynchronizationContextEventLoopSignal/post_on_event_loop,Realms.SynchronizationContextEventLoopSignal/release_eventloop)
at Realms.SynchronizationContextEventLoopSignal.Install () [0x0003b] in C:\jenkins\workspace\realm_realm-dotnet_PR\Realm\Realm\Native\SynchronizationContextEventLoopSignal.cs:122
at Realms.NativeCommon.Initialize () [0x00112] in C:\jenkins\workspace\realm_realm-dotnet_PR\Realm\Realm\Native\NativeCommon.cs:91
at Realms.SharedRealmHandle..cctor () [0x00000] in C:\jenkins\workspace\realm_realm-dotnet_PR\Realm\Realm\Handles\SharedRealmHandle.cs:128
So, main point that I can't create Realm instance.
Is launched iphone simulator necessary to work with Realm?
Are there some possibility to create unit tests for Realm?
Or should it be some kind of Auto tests?

As I found, solution is iOS Unit Test App (Solution -> Add -> New Project -> iOS -> Tests -> Unit Test App).
There are few disadvantages, but it is possible to test Realm. The next challenge is to run it and get result with TeamCity.

Need help connecting to MongoDB cluster on Android

I'm working on a mobile app with Xamarin Forms and intend to use a Mongo database.
I'm using Visual Studio 2019 with the MongoDB Driver Version 2.9.2 and android 28 as target SDK version.
I created a cluster on MongoDB Atlas, whitelisted all IP addresses for now, and tried to connect the app to the cluster with the connection string I was provided for the cluster(in the code below I replaced the real username and password with placeholders).
Here's the code:
private const string CONNECTION_STRING = "mongodb+srv://username:password#cluster0-uswax.mongodb.net/test?retryWrites=true&w=majority";
var client = new MongoClient(CONNECTION_STRING);
If I run the program with the Android emulator, the line where the MongoClient is created is where the program crashes with the following exception:
System.AggregateException
Message=Error resolving name servers (Value cannot be null.
Parameter name: source) (Could not find file "/etc/resolv.conf")
Source=DnsClient
StackTrace:
at DnsClient.NameServer.ResolveNameServers (System.Boolean skipIPv6SiteLocal, System.Boolean fallbackToGooglePublicDns) [0x0005e] in <93b57b4b99c64a96a2c065ea9ae1fc1f>:0
at DnsClient.LookupClient..ctor () [0x00000] in <93b57b4b99c64a96a2c065ea9ae1fc1f>:0
at MongoDB.Driver.Core.Configuration.ConnectionString.Resolve (System.Boolean resolveHosts) [0x00011] in <bfbe70fcd6734952960e694cb03fd3c6>:0
at MongoDB.Driver.MongoUrl.Resolve (System.Boolean resolveHosts) [0x00015] in <f2c302ca191a4adf889da299a582e348>:0
at MongoDB.Driver.MongoClientSettings.FromUrl (MongoDB.Driver.MongoUrl url) [0x0001b] in <f2c302ca191a4adf889da299a582e348>:0
at MongoDB.Driver.MongoClientSettings.FromConnectionString (System.String connectionString) [0x00006] in <f2c302ca191a4adf889da299a582e348>:0
at MongoDB.Driver.MongoClient..ctor (System.String connectionString) [0x00000] in <f2c302ca191a4adf889da299a582e348>:0
at Socializer.Helpers.MongoCrud..ctor (System.String connectionString, System.String databaseName) [0x00008] in D:\Data\projects\xamarin\Socializer\Socializer\Socializer\Helpers\MongoCrud.cs:18
at Socializer.App..ctor () [0x0001b] in D:\Data\projects\xamarin\Socializer\Socializer\Socializer\App.xaml.cs:27
at Socializer.Droid.MainActivity.OnCreate (Android.OS.Bundle savedInstanceState) [0x0002f] in D:\Data\projects\xamarin\Socializer\Socializer\Socializer.Android\MainActivity.cs:24
at Android.App.Activity.n_OnCreate_Landroid_os_Bundle_ (System.IntPtr jnienv, System.IntPtr native__this, System.IntPtr native_savedInstanceState) [0x00011] in <11a340ccc8de43f09c97400139266ef5>:0
at (wrapper dynamic-method) Android.Runtime.DynamicMethodNameCounter.8(intptr,intptr,intptr)
When I was looking for a solution to this problem I found this bug report,
stating that "Android is not currently a supported platform for the .NET driver"
Does that mean I cannot use MongoDB for Android applications or is there any other way? Thanks!
Edit: I also found this possible solution. The user that provided the answer states that "from Android 8 (Oreo), access to net.dns has been removed". Indeed when I remove android:targetSdkVersion="28" from my AndroidManifest.xml, the program no longer crashes, but that won't be an option once I want to upload the app to the play store.
The solution above is based on a custom implementation to get DNS servers but I do not know how I would implement this function into my code. I would appreciate it a lot if anyone could help me with that.
Here is the function:
public List<IPEndPoint> GetDnsServers()
{
var context = Android.App.Application.Context;
List<IPEndPoint> endPoints = new List<IPEndPoint>();
ConnectivityManager connectivityManager =
(ConnectivityManager)context.GetSystemService(MainActivity.ConnectivityService);
Network activeConnection = connectivityManager.ActiveNetwork;
var linkProperties = connectivityManager.GetLinkProperties(activeConnection);
foreach (InetAddress currentAddress in linkProperties.DnsServers)
{
IPEndPoint endPoint = new IPEndPoint(IPAddress.Parse(currentAddress.HostAddress), 53);
endPoints.Add(endPoint);
}
return endPoints;
}

I got this issue too. It turns out that, MongoDB Driver on Xamarin Android doesn't support DNS Seedlist Connection Format (starts from "mongodb+srv://") very well. So you have to use Standard Connection String Format (starts from "mongodb://").
Please go to Atlas and find your Standard Connection String by selecting an old version driver like C#/.NET 2.4
For more discription of these two connection ways, refer to this

Timed out waiting for result of ClearAppData2 when running Xamarin UI Tests for Android

I've created automatic Android and iOS UI-Tests for my Xamarin application with the Xamarin UITest framework. When running the tests locally, they work fine, but when running them on the Bitrise CI, the iOS tests run fine, but the Android UI Tests keep failing with the following exception:
StartFirstActivity_WaitForActivity_ExpectButtonToHaveText
SetUp : System.Exception : Timed out waiting for result of ClearAppData2
Stack trace:
at Xamarin.UITest.Shared.Android.Commands.CommandAdbClearAppData.Execute (IProcessRunner processRunner, IAndroidSdkTools androidSdkTools) <0x38b3e90 + 0x0064b> in <filename unknown>:0
at Xamarin.UITest.Shared.Execution.Executor.Execute[TDep1,TDep2] (ICommand2 command) <0x32b6478 + 0x00092> in <filename unknown>:0
at Xamarin.UITest.Shared.Android.LocalAndroidAppLifeCycle.EnsureInstalled (Xamarin.UITest.Shared.Android.ApkFile appApkFile, Xamarin.UITest.Shared.Android.ApkFile testServerApkFile) <0x37418c8 + 0x0017a> in <filename unknown>:0
at Xamarin.UITest.Android.AndroidApp..ctor (IAndroidAppConfiguration appConfiguration) <0x31a15e8 + 0x0047a> in <filename unknown>:0
at Xamarin.UITest.Configuration.AndroidAppConfigurator.StartApp (AppDataMode appDataMode) <0x30b4298 + 0x00063> in <filename unknown>:0
at SightPlayer.Core.Test.AppInitializer.StartApp (Platform platform) <0x30b2448 + 0x000ef> in <filename unknown>:0
at SightPlayer.Core.Test.Tests.BeforeEachTest () <0x30b23f8 + 0x00013> in <filename unknown>:0
at (wrapper managed-to-native) System.Reflection.MonoMethod:InternalInvoke (System.Reflection.MonoMethod,object,object[],System.Exception&)
at System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) <0x30b2208 + 0x00093> in <filename unknown>:0
Android test are running with Xamarin.UITest version 1.3.5. This is important, as there seems to have been a bug until version 1.3.3. I've also tried ignoring failing tests, but then the test-runner fails with other Android tests. Interestingly enough that sometimes individual tests pass.
Has anyone encountered this behaviour before? Do you have any advice on how to fix this?
When decompiling CommandAdbClearAppData (which throws the exception), I see
// ISSUE: reference to a compiler-generated field
string str1 = string.Format("/data/data/{0}/files/calabash_failure.out", (object)executeCAnonStorey0.svr);
// ISSUE: reference to a compiler-generated field
string str2 = string.Format("/data/data/{0}/files/calabash_finished.out", (object)executeCAnonStorey0.svr);
while (DateTime.UtcNow < utcNow + TimeSpan.FromSeconds(10.0))
{
if (func(string.Format("ls {0}", (object)str1)).Output.Trim().Equals(str1))
throw new Exception("Clear app data failed with " + func(string.Format("cat {0}", (object)str1)).Output);
if (func(string.Format("ls {0}", (object)str2)).Output.Trim().Equals(str2) && func(string.Format("cat {0}", (object)str2)).Output.Trim().Equals("SUCCESSFUL"))
return;
}
throw new Exception("Timed out waiting for result of ClearAppData2");
which indicates that the generated file could not be found within ten seconds. Could it be, that the emulator is simply too slow and the emulator takes longer than ten seconds to create those files?

Could it be, that the emulator is simply too slow and the emulator takes longer than ten seconds to create those files?
Yes, that could be the problem.
Do you have any advice on how to fix this?
The latest dev builds of the Xamarin.UITest nuget package have increased that timeout interval from 10 seconds to 60 seconds.
Try Xamarin.UITest 1.3.6.1476-dev or newer.

I solved this issue uploading a unsigned version of the APK to my testing device (same thing for Xamarin Android Player). I had to uncheck the "Sign the .APK file" box from the Android Package Signing option in the project properties. The WaitTimes way didn't work for me.

I think you need to look at some Configuration
If your app is not waiting to launch the test you could implement WaitTimes.
Create a class like this:
public class WaitTimes : IWaitTimes
{
public TimeSpan GestureWaitTimeout
{
get { return TimeSpan.FromMinutes(1); }
}
public TimeSpan WaitForTimeout
{
get { return TimeSpan.FromMinutes(1); }
}
}
Then implement it like this:
_app = ConfigureApp
.Android
.EnableLocalScreenshots()
.ApkFile(apkFile)
.DeviceSerial("###")
.ApiKey("###")
.Debug()
.WaitTimes(new WaitTimes())
.StartApp();
Otherwise you could just wait for a specific element to load, like this:
_app.WaitForElement(c => c.Marked("Login"), "Time out expired", TimeSpan.FromSeconds(15));
var result = _app.Query(c => c.Marked("Login"));
Assert.AreEqual(1,result.Length);
_app.Screenshot("Test passed with success");
Here is some more information about WaitTime and WaitForElement that could be helpful.

Calling Mono exe from C does not find libc

In Ubuntu, I am calling a C# executable from C using Mono (v3.2.8) and the embedded Mono runtime. When I call the exe (.NET 4.5) from the command line (ie, mono testFile.exe), it works fine. However, when I run my C test program, it throws a C# exception:
libc at at (wrapper managed-to-native) System.Platform:uname (intptr)
at System.Platform.get_IsMacOS () [0x00000] in <filename unknown>:0
at System.Net.WebRequest.GetSystemWebProxy () [0x00000] in <filename unknown>:0
at System.Net.WebRequest.GetDefaultWebProxy () [0x00000] in <filename unknown>:0
at System.Net.WebRequest.get_DefaultWebProxy () [0x00000] in <filename unknown>:0
at System.Net.GlobalProxySelection.get_Select () [0x00000] in <filename unknown>:0
at System.Net.HttpWebRequest..ctor (System.Uri uri) [0x00000] in <filename unknown>:0
at (wrapper remoting-invoke-with-check) System.Net.HttpWebRequest:.ctor (System.Uri)
at System.Net.HttpRequestCreator.Create (System.Uri uri) [0x00000] in <filename unknown>:0
at System.Net.WebRequest.Create (System.Uri requestUri) [0x00000] in <filename unknown>:0
at System.Net.WebRequest.Create (System.String requestUriString) [0x00000] in <filename unknown>:0
at MyClass.MainClass.Main (System.String[] args) [0x00000] in <filename unknown>:0
I've narrowed it down to this one line of code:
WebRequest request = WebRequest.Create("http://www.google.com");
Looking through the call stack and the mono source code, I believe the failure is associated with the calling of the native 'uname' function in libc.so (the CheckOS() function, line 50 of mcs/class/System/System/Platform.cs):
if (uname (buf) == 0) {
I think what is happening is that the p/Invoke layer cannot locate libc.so. However, when I make the same call in my executable's Main() function, it executes fine, I am confused why it works in one place but not the other. It is also strange that the exception message is not a DllNotFoundException, but rather this generic "libc" message (though I have confirmed that I get the same message when I try to p/Invoke with a bogus .so).
My C code:
int main(int argc,const char* argv[]) {
MonoDomain* domain=mono_jit_init("testFile.exe");
MonoAssembly* assembly=mono_domain_assembly_open(domain,"testFile.exe");
MonoImage* image=mono_assembly_get_image(assembly);
const char* args[1];
args[0]="testFile.exe";
mono_jit_exec(domain,assembly,1,(char**) args);
}
My C# code:
namespace MyClass {
class MainClass {
public static void Main (string[] args) {
WebRequest request=WebRequest.Create("http://www.google.com");
}
}
}
gcc compile options are:
gcc cTest.c -I/usr/include/mono-2.0 -DREENTRANT -lmono-2.0 -lm -lrt -ldl -lpthread
mono compile options are:
dmcs -out:testFile.exe -platform:anycpu -sdk:4.5 -target:exe -unsafe+ -main:MyClass.MainClass -reference:System,System.Configuration,System.Data,System.ServiceModel,System.Web,System.Xml *.cs
Update:
I used MONO_LOG_LEVEL and MONO_LOG_MASK to trace the .so search sequence and found that the sequence on the successful call was entirely different from the unsuccessful one. So it is searching, just not very well. I then copied my libc.so.6 to the current directory, renamed to libc.so, and then set LD_LIBRARY_PATH to the same location. This gave me success. I am now having my Linux guru look into what can be done to make this solution more 'correct', but at least I have a running program. This may be the same problem as mine (though the solution's not working for me).

The problem is you are missing the dll mapping (mono_config_parse). The following will work with mono 3.x and 4.x embedding and avoid your libc error.
#include <mono/jit/jit.h>
#include <mono/metadata/environment.h>
#include <stdlib.h>
int
main(int argc, char* argv[]) {
MonoDomain *domain;
const char *file;
int retval;
mono_config_parse (NULL);
domain = mono_jit_init ("textFile.exe");
MonoAssembly *assembly;
assembly = mono_domain_assembly_open (domain, "testFile.exe");
mono_jit_exec (domain, assembly, argc, argv);
retval = mono_environment_exitcode_get ();
mono_jit_cleanup (domain);
return retval;
}
Certain features of the runtime like Dll remapping depend on a configuration file, to load the configuration file, just add:
mono_config_parse (NULL);
Which will load the Mono configuration file (typically /etc/mono/config).
http://www.mono-project.com/docs/advanced/embedding
FYI: On Ubuntu 15.04, I am using:
gcc main.c `pkg-config --cflags --libs mono-2`
You can update that of course to grab the mono-sgen vs. the boehm jit.
On OS-X:
gcc main.c -m32 -framework Foundation -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.10.sdk \
-lmonosgen-2.0 \
-I/Library/Frameworks/Mono.framework/Headers/mono-2.0 \
-L/Library/Frameworks/Mono.framework/Libraries

I've run into this issue as well. What I noticed is that the mkbundle output lists the assemblies which it embeds, and that the System.Net.dll was not included. After adding it manually on the mkbundle command line, it all worked fine.
The command line I'm using now:
mkbundle my.exe --deps --keeptemp --static --config /etc/mono/configlibc --machine-config /etc/mono/4.5/machine.config System.Net.dll -o bssetup.exe
The configlibc file is a modified copy of the default config file in that directory. The modifications were to remove all mapping lines, except the one for libc.
Hope it helps anyone!

Based on your update, it looks like the application is searching for libc.so instead of libc.so.6. You got it working by manually pointing your LD_LIBRARY_PATH to the current folder having the libc.so that you copied.
Suggestion: ask your Linux guru to symlink libc.so to libc.so.6 in your normal search paths for your application to work.

Error with Unity iOS compile: Cross Compilation job Mono.WebBrowser.dll failed

have been working on a project intended for iOS deployment. Until recently, we have been building and deploying to our client via webplayer. However, I am now attempting to shift to releasing builds on iOS . But, no matter what I try, when I go to compile the project I receive the following error messages:
Cross compilation job Mono.WebBrowser.dll failed.
UnityEngine.UnityException: Failed AOT cross compiler: /Applications/Unity_45/Unity.app/Contents/PlaybackEngines/iOSSupport/Tools/OSX/mono-xcompiler --aot=full,asmonly,nodebug,static,outfile="Mono.WebBrowser.dll.s" "Mono.WebBrowser.dll" current dir : /Users/admin/Desktop/UI_gg_current/Temp/StagingArea/Data/Managed
Env: Apple_PubSub_Socket_Render = '/tmp/launch-7SV8Ex/Render'
LOGNAME = 'admin'
PATH = '/usr/bin:/bin:/usr/sbin:/sbin'
TMPDIR = '/var/folders/7c/s32nkpmx0yvgw4mmw_5vhxx40000gn/T/'
MONO_PATH = '/Users/admin/Desktop/UI_gg_current/Temp/StagingArea/Data/Managed'
SSH_AUTH_SOCK = '/tmp/launch-wpdtRI/Listeners'
USER = 'admin'
GC_DONT_GC = 'yes please'
Apple_Ubiquity_Message = '/tmp/launch-cfnoHv/Apple_Ubiquity_Message'
SHELL = '/bin/bash'
__CF_USER_TEXT_ENCODING = '0x1F5:0:0'
GAC_PATH = '/Users/admin/Desktop/UI_gg_current/Temp/StagingArea/Data/Managed'
HOME = '/Users/admin'
COMMAND_MODE = 'unix2003'
result file exists: False. Timed out: False
stdout:
stderr:
at UnityEditor.MonoProcessUtility.RunMonoProcess (System.Diagnostics.Process process, System.String name, System.String resultingFile) [0x00000] in <filename unknown>:0
at UnityEditor.MonoCrossCompile.CrossCompileAOT (BuildTarget target, System.String crossCompilerAbsolutePath, System.String assembliesAbsoluteDirectory, CrossCompileOptions crossCompileOptions, System.String input, System.String output, System.String additionalOptions) [0x00000] in <filename unknown>:0
at UnityEditor.MonoCrossCompile+JobCompileAOT.ThreadPoolCallback (System.Object threadContext) [0x00000] in <filename unknown>:0
UnityEditor.HostView:OnGUI()
and
Error building Player: UnityException: Cross compilation failed.
I am using Unity 4.5. To date I have : deleted third party dlls (including xml.linq.dll) , removed any instance of Lambda search operators (=>), and deleted the temp folder because I have seen these approaches used in similar situations (I know some aspects of Linq are not supported in iOS cross compile).
I have looked at similar issues such as this one: http://answers.unity3d.com/questions/439367/cross-compilation-failed-csharpdll.html. But, I am so perplexed, because it isn't the CSharp assembly causing my problem (which means it isn't one of my scripts?) I am not sure why it would even be including a WebBrowser.dll for an iOS build. Any help is greatly appreciated, as I feel I have searched far and wide for a resolution with no luck.

See the resolution that for this question here.