Develop Reference

ASP.NET Web API Test instance initialization

I am writing some integration tests for my web API, which means that it has to be running during the execution of the tests. Is there any way to run it with an in-memory database instead of a real one based on SQL Server?
Also, I need to run a few instances at a time, so I need somehow to change the base address of each of them to be unique. For example, I could append to the base URL these instance IDs, that are mentioned in the code below.
Here is the code which I am using to run a new instance for my tests:
public static class WebApiHelper
{
private const string ExecutableFileExtension = "exe";
private static readonly Dictionary<Guid, Process> _instances = new();
public static void EnsureIsRunning(Assembly? assembly, Guid instanceId)
{
if (assembly is null)
throw new ArgumentNullException(nameof(assembly));
var executableFullName = Path.ChangeExtension(
assembly.Location, ExecutableFileExtension);
_instances.Add(instanceId, Process.Start(executableFullName));
}
public static void EnsureIsNotRunning(Guid instaceId)
=> _instances[instaceId].Kill();
}
Talking in general, is this a good way to create test instances, or maybe I am missing something? Asking this, because maybe there is another 'legal' way to achieve my goal.

Okay, so in the end, I came up with this super easy and obvious solution.
As was mentioned in the comments - using the in-memory database is not the best way to test, because relational features are not supported if using MS SQL.
So I decided to go another way.
Step 1: Overwrite the connection strings.
In my case, that was easy since I have a static IConfiguration instance and was need just to overwrite the connection string within that instance.
The method looks as follows:
private const string ConnectionStringsSectionName = "ConnectionStrings";
private const string TestConnectionStringFormat = "{0}_Test";
private static bool _connectionStringsOverwitten;
private static void OverwriteConnectionStrings()
{
if (_connectionStringsOverwitten)
return;
var connectionStrings = MyStaticConfigurationContainer.Configuration
.AsEnumerable()
.Where(entry => entry.Key.StartsWith(ConnectionStringsSectionName)
&& entry.Value is not null);
foreach (var connectionString in connectionStrings)
{
var builder = new SqlConnectionStringBuilder(connectionString.Value);
builder.InitialCatalog = string.Format(TestConnectionStringFormat,
builder.InitialCatalog);
MyStaticConfigurationContainer.Configuration[connectionString.Key] = builder.ConnectionString;
}
_connectionStringsOverwitten = true;
}
Of course, you would need to handle the database creation and deletion before and after running the tests, otherwise - your test DBs may become a mess.
Step 2: Simply run your web API instance within a separate thread.
In my case, I am using the NUnit test framework, which means I just need to implement the web API setup logic within the fixture. Basically, the process would be more or less the same for every testing framework.
The code looks as follows:
[SetUpFixture]
public class WebApiSetupFixture
{
private const string WebApiThreadName = "WebApi";
[OneTimeSetUp]
public void SetUp() => new Thread(RunWebApi)
{
Name = WebApiThreadName
}.Start();
private static void RunWebApi()
=> Program.Main(Array.Empty<string>());
// 'Program' - your main web app class with entry point.
}
Note: The code inside Program.Main(); will also look for connection strings in the MyStaticConfigurationContainer.Configuration which was changed in the previous step.
And that's it! Hope this could help somebody else :)

How to Integrate NodeJs in Existing .Net MVC application Using EdgeJs?

Can any one suggest another way to integrate NodeJs in .Net MVC application? I am now using the following code:
public class Startup
{
public async Task<object> Invoke(dynamic input)
{
DepartmentRep person = new DepartmentRep(new MvcAppUsingEdgeJSMongoDbContext());
var department= person.GetAllDepartments();
//var department = "hello";
return department;
}
}
public class DepartmentController : Controller
{
DepartmentRepository departmentRepository = new DepartmentRepository(new MvcAppUsingEdgeJSMongoDbContext());
string connectionString = ConfigurationManager.AppSettings["connectionString"].ToString();
public ViewResult Index()
{
// var clrMethod = Edge.Func("DepartmentRep.cs");
var getData = Edge.Func("./DepartmentRep.dll");
// return View(clrMethod);
return View(departmentRepository.GetAllDepartments());
}
}

It seems to me, you may have a misunderstanding of the EdgeJs use case.
Your Startup/Invoke class/Signature is meant to be called from Node(JavaScript),
And from the code you are showing it looks like you are loading .Net from .Net
Also , as the Invoke signature suggest, It should be asynchronous.
If you want to use node from .Net side. You should check the project documentation from
scripting-nodejs-from-clr downwards.
var func = Edge.Func(#"
return function (data, callback) {
callback(null, 'Node.js welcomes ' + data);
}
");
As you can see there the wrapped code is Javascript, this time running in .Net more specifically running in Node.
The perfect use case IMMO is the Socket-Server, that is, something Node does better than .Net (IMMO again)
Which is in perfect contrast with the .Net Ado Sql Server access from NodeJs, a .Net Specialization from NodeJs context

Is it possible to execute C# code represented as string?

On my form I have a button click
private void button1_Click(object sender, EventArgs e)
{
do something
}
How on the click would I load my do something from a text file, for example my text file looks like this:
MessageBox.Show("hello");
label1.Text = "Hello";
on click it does everything in my text file, if possible.

Here is a very simple example, just to prove this is possible. Basically, you use CodeDomProvider to compile source at runtime, then execute using reflection.
var provider = CodeDomProvider.CreateProvider("C#");
string src=#"
namespace x
{
using System;
public class y
{
public void z()
{
Console.WriteLine(""hello world"");
}
}
}
";
var result = provider.CompileAssemblyFromSource(new CompilerParameters(), src);
if (result.Errors.Count == 0)
{
var type = result.CompiledAssembly.GetType("x.y");
var instance = Activator.CreateInstance(type);
type.GetMethod("z").Invoke(instance, null);
}
Edit
As #Agat points out, the OP seems to require a sort of scripting framework (it makes use of label1, a property of the current object), whereas my answer above obviously does not provide that. The best I can think of is a limited solution, which would be to require dependencies to be specified explicitly as parameters in the "script". Eg, write the scripted code like this:
string src = #"
namespace x
{
using System.Windows;
public class y
{
public void z(Label label1)
{
MessageBox.Show(""hello"");
label1.Text = ""Hello"";
}
}
}
";
Now you can have the caller examine the parameters, and pass them in from the current context, again using reflection:
var result = provider.CompileAssemblyFromSource(new CompilerParameters(), src);
if (result.Errors.Count == 0)
{
var type = result.CompiledAssembly.GetType("x.y");
var instance = Activator.CreateInstance(type);
var method = type.GetMethod("z");
var args = new List<object>();
// assume any parameters are properties/fields of the current object
foreach (var p in method.GetParameters())
{
var prop = this.GetType().GetProperty(p.Name);
var field = this.GetType().GetField(p.Name);
if (prop != null)
args.Add(prop.GetValue(this, null));
else if (field != null);
args.Add(field.GetValue(this));
else
throw new InvalidOperationException("Parameter " + p.Name + " is not found");
}
method.Invoke(instance, args.ToArray());
}

Like the other answers have stated, it isn't an easy thing to implement and can possibly be done through reflection depending on how advanced your scripts are.
But no one #BrankoDimitrijevic mentioned Roslyn and it is a great tool. http://msdn.microsoft.com/en-us/vstudio/roslyn.aspx
It hasn't been updated in quite awhile (Sept.2012) and doesn't have all of the features of C# implemented, however, it did have a lot of it implemented when I played around with this release.
By adding your assembly as a reference to the scripting session, you're able to gain access to all of your assembly's types and script against them. It also supports return values so you can return any data that a scripted method generates.
You can find what isn't implemented here.
Below is a quick and dirty example of Roslyn that I just wrote and tested. Should work right out of box after installing Roslyn from NuGet. The small bloat at the initialization of the script engine can easily be wrapped up in a helper class or method.
The key is passing in a HostObject. It can be anything. Once you do, your script will have full access to the properties. Notice that you just call the properties and not the host object in the script.
Basically, your host object will contain properties of the data you need for your script. Don't necessarily think of your host object as just a single data object, but rather a configuration.
public class MyHostObject
{
public string Value1 { get; set; }
public string Value2 { get; set; }
}
public class RoslynTest
{
public void Test()
{
var myHostObject = new MyHostObject
{
Value1 = "Testing Value 1",
Value2 = "This is Value 2"
};
var engine = new ScriptEngine();
var session = engine.CreateSession(myHostObject);
session.AddReference(myHostObject.GetType().Assembly.Location);
session.AddReference("System");
session.AddReference("System.Core");
session.ImportNamespace("System");
// "Execute" our method so we can call it.
session.Execute("public string UpdateHostObject() { Value1 = \"V1\"; Value2 = \"V2\"; return Value1 + Value2;}");
var s = session.Execute<string>("UpdateHostObject()");
//s will return "V1V2" and your instance of myHostObject was also changed.
}
}

No. You can not.
At least in any simple way.
The thing you want is something like eval('do something') from javascript.
That's not possible to do with C#. C# is a language which needs compilation before execution unlike javascript (for instance).
The only way to implement that is to build your own (pretty complicated as for beginner) parser and execute it in such way.
UPDATED:
Actually, as JDB fairly noticed, that's really not the only way. I love programming! There are so many ways to make a freakky (or even sometimes that really can be necessary for some custom interesting tasks (or even learning)!) code. he he
Another approach I've got in my mind is building some .cs file, then compiling it on-the-fly and working with it as some assembly or some other module. Right.

dynamic method and the MethodAccessException

given the following classes:
class SomeBuilder<T>
{
public static object Build(int index)
{
...
}
}
class SomeHelper
{
public object GetBuildObj(object value)
{
var valuetype = value.GetType();
var methodinfo = typeof(SomeBuilder<>).MakeGenericType(valuetype).GetMethod("Build");
var handler = SomeDynamicHelper.GetMethodInvoker(methodinfo);
var result = hander(null, new object[]{1});
}
}
SomeBuilder was a generic type so i need a call to MakeGenericType() to make things right.
when i pass a normal type like 'class person' for the value, everything just works, that`s fine.
but when i pass a anonymous type like: new { id=1 }, the handler was successfully created. but invoke this dynamic handler i got a MethodAccessException with these messages:
"method "SomeDynamicHelper.(System.Object, System.Objec[])" try to access method "SomeBuilder'1<<>f__AnonymousType0'1<System.Int32>>.Build(int)" failed.
any help would be appreciated, thx.
btw, if you are interested in SomeDynamicHelper, plz see:
http://www.codeproject.com/Articles/14593/A-General-Fast-Method-Invoker
edit1:
i did the call in main like this:
static void Main(string[] args)
{
// pass a normal class, this will be fine
var value = new Person { id = 1};
new SomeHelper().GetBuildObj(value);
// pass a anonymous type
var value = new { id = 1};
new SomeHelper().GetBuildObj(value); // oops, got a exception here!
}
edit2:
based on the comment i changed my code:
class SomeHelper
{
public object GetBuildObj(object value)
{
//this time i do not use the value, but create a new inner value:
var valuenew = new { id = 1 };
var valuetype = valuenew.GetType();
var methodinfo = typeof(SomeBuilder<>).MakeGenericType(valuetype).GetMethod("Build");
var handler = SomeDynamicHelper.GetMethodInvoker(methodinfo);
var result = hander(null, new object[]{1});
}
}
well, this time there is no exception, but...unfortunately a new problem occured...may be i should open a new thread for the new problem.
thank you guys, for your attentions.
edit3:
hi, after some digging, i also found some useful information. say, the SomeDynamicHelper.GetMethodInvoker() code as below:
DynamicMethod dynamicMethod = new DynamicMethod(string.Empty, typeof(object), new Type[] { typeof(object), typeof(object[]) }, methodInfo.DeclaringType.Module);
this is the core we used here to dynamic create a method. for our context, we need to declare the anonymous type in same assembly with the SomeHelper and SomeBuilder. but, if we can`t do the declaration, what should we do?
ok, you can call DynamicMethod() with last parameter(the skipVisibility), set to true!
hope this will help others with the same problem :)

"method "SomeDynamicHelper.(System.Object, System.Objec[])" try to access method "SomeBuilder'1<<>f__AnonymousType0'1>.Build(int)"
From this you can see that dynamic method try to run an internal\private method called Build, for that you got MethodAccessException.
(The anonymous type is kept in a new generated class)
Adding InternalVisibleTo not always helping because it's helping only if you can rewrite the anonymous type assembly (manually or with interception) and only if the type and method are internals and not private.
In dynamic method you can bind the method to type\module, and to skip visibility check, but this help to access private members of the specified module, so again if the type you trying to access is in a different assembly and the type\method are private you can't do anything.
Well almost. There is a "secret" attribute that you inject to your assembly, called IgnoreAccessChecksTo and then in addition to bounded module and skip visibility maybe it will work.

You can try using [assembly: InternalsVisibleTo("Anonymously Hosted DynamicMethods Assembly")] in the same project where you define the anonymous type.

I had a similar error with a C# class I tried to inject using IKVM-converted Guice. The fix was simply making the affected class (in this case probably SomeBuilder) public and everything worked fine.

Activator.CreateInstance can't find the constructor (MissingMethodException)

I have a class which has the following constructor
public DelayCompositeDesigner(DelayComposite CompositeObject)
{
InitializeComponent();
compositeObject = CompositeObject;
}
along with a default constructor with no parameters.
Next I'm trying to create an instance, but it only works without parameters:
var designer = Activator.CreateInstance(designerAttribute.Designer);
This works just fine, but if I want to pass parameters it does not:
var designer = Activator.CreateInstance(designerAttribute.Designer, new DelayComposite(4));
This results in an MissingMethodException:
Constructor voor type
Vialis.LightLink.Controller.Scenarios.Composites.DelayCompositeDesigner
was not found
Any ideas here?
The problem is I really need to pass an object during construction.
You see I have a designer which loads all the types that inherit from the CompositeBase. These are then added to a list from which the users can drag them to a designer. Upon doing so an instance of the dragged is added to the designer. Each of these classes have custom properties defined on them:
[CompositeMetaData("Delay","Sets the delay between commands",1)]
[CompositeDesigner(typeof(DelayCompositeDesigner))]
public class DelayComposite : CompositeBase
{
}
When the user selects an item in the designer, it looks at these attributes in order to load up a designer for that type. For example, in the case of the DelayComposite it would load up a user control which has a label and a slider which allow the user to set the "Delay" property of the DelayComposite instance.
So far this works fine if I don't pass any parameters to the constructor. The designer creates an instance of the DelayCompositeDesigner and assigns it to the content property of a WPF ContentPresenter.
But since that designer needs to modify the properties of the selected DelayComposite
in the designer, I have to pass this instance to it. That is why the constructor looks lie this:
public DelayCompositeDesigner(DelayComposite CompositeObject)
{
InitializeComponent();
compositeObject = CompositeObject;
}
Suggestions are welcome
#VolkerK
The result of your code is this:
<---- foo
Vialis.LightLink.Controller.Scenarios.Composites.DelayCompositeDesignerVoid
.ctor()
Vialis.LightLink.Controller.Scenarios.Composites.DelayCompositeDesignerVoid
.ctor(Vialis.LightLink.Controller.Scenarios.Composites.DelayComposite)
param:Vialis.LightLink.Controller.Scenarios.Composites.DelayComposite
foo ---->
Leppie, you were correct, I had for some reason referenced the Composites assembly in my UI application... which is not something I should have done as I was loading it at runtime. The following code works:
object composite = Activator.CreateInstance(item.CompositType,(byte)205);
var designer = Activator.CreateInstance(designerAttribute.Designer, composite);
As you can see the code does not have knowledge of the DelayComposite type.
This solves the current problem, but introduces many new ones for what I want to achieve,
either way thank you and thank you to everyone who has replied here.
As for the following code, suggested by multiple people:
var designer = Activator.CreateInstance(
designerAttribute.Designer,
new object[] { new DelayComposite(4) }
);
The Activator.CreateInstance has a signature that looks like this:
Activator.CreateInstance(Type type, params object[] obj)
So it should accept my code, but I will try the suggested code
UPDATE:
I've tried this as suggested:
var designer = Activator.CreateInstance(designerAttribute.Designer, new object[] { new DelayComposite(4)});
The result is the same.

I would think that your call would need to be:
var designer = Activator.CreateInstance(designerAttribute.Designer, new object[] { new DelayComposite(4) });
Unless, of course, it is that, in which case the answer is not immediately obvious.

I think you are dealing with a Type mismatch.
Likely the assembly is referenced in different places, or they are compiled against different versions.
I suggest you iterate through the ConstructorInfo's and do a paramtype == typeof(DelayComposite) on the appropriate parameter.

Though I hate printf-like debugging ...
public static void foo(Type t, params object[] p)
{
System.Diagnostics.Debug.WriteLine("<---- foo");
foreach(System.Reflection.ConstructorInfo ci in t.GetConstructors())
{
System.Diagnostics.Debug.WriteLine(t.FullName + ci.ToString());
}
foreach (object o in p)
{
System.Diagnostics.Debug.WriteLine("param:" + o.GetType().FullName);
}
System.Diagnostics.Debug.WriteLine("foo ---->");
}
// ...
foo(designerAttribute.Designer, new DelayComposite(4));
var designer = Activator.CreateInstance(designerAttribute.Designer, new DelayComposite(4));
What does that print in the visual studio's output window?

If you want to call this contructor...
public DelayCompositeDesigner(DelayComposite CompositeObject)
...just use this:
var designer = Activator.CreateInstance(typeof(DelayCompositeDesigner), new DelayComposite(4));
or
var designer = Activator.CreateInstance<DelayCompositeDesigner>(new DelayComposite(4));

I had a similar issue, however my problem was due to the visibility of the constructor. This stack overflow helped me:
Instantiating a constructor with parameters in an internal class with reflection

I discovered another way of creating an instance of an object without calling the constructor at all while answering another question on SF.
In the System.Runtime.Serialization namespace there is a function FormatterServices.GetUninitializedObject(type) that will create an object without calling constructor.
If you look at that function in Reflector you will see it is making an external call. I don't know how black magic is actually happening under the hood. But I did prove to myself that the constructor was never called but the object was instantiated.

When I encountered this problem, I was using a method that returned the parameter list to plug in to Activator.CreateInstance and it had a different number of arguments than the constructor of the object I was trying to create.

In my case, this code work good with .NET Framework but does not work in .NET Core 3.1. It throws ExecutionEngineException which is uncatchable. But when I change target to .NET 5, it works perfectly. Hope this help some one.
Type type = assembly.GetType(dllName + ".dll");
Activator.CreateInstance(type ), new Stream[] { stream };

You can use the following overload on CreateInstance:
public static Object CreateInstance(
Type type,
Object[] args
)
And in your case it'd be (I think):
var designer = Activator.CreateInstance(
typeof(DelayCompositeDesigner),
new object[] { new DelayComposite(4) }
);

I found a solution to the problem, I was struggling with the same issue.
Here is my activator:
private void LoadTask(FileInfo dll)
{
Assembly assembly = Assembly.LoadFrom(dll.FullName);
foreach (Type type in assembly.GetTypes())
{
var hasInterface = type.GetInterface("ITask") != null;
if (type.IsClass && hasInterface)
{
var instance = Activator.CreateInstance(type, _proxy, _context);
_tasks.Add(type.Name, (ITask)instance);
}
}
}
And here is my class to activate, note that I had to change the constructor params to objects, the only way I could get it to work.
public class CalculateDowntimeTask : Task<CalculateDowntimeTask>
{
public CalculateDowntimeTask(object proxy, object context) :
base((TaskServiceClient)proxy, (TaskDataDataContext)context) { }
public override void Execute()
{
LogMessage(new TaskMessage() { Message = "Testing" });
BroadcastMessage(new TaskMessage() { Message = "Testing" });
}
}