Improve error messaging in Q# test & application projects

[vadym-kl]

What you would like the feature to accomplish.

Currently when a single test fails the error message is verbose, hard to read and exposes C# code generation internals.
See below for an example. Similar improvement would be nice to have in the code that is generated when creating Q# console application.

Additional context

Consider a test project with a single qsharp file with a single test that fails:

namespace qsharp_unit_test_example {
    
    open Microsoft.Quantum.Canon;
    open Microsoft.Quantum.Diagnostics;
    open Microsoft.Quantum.Intrinsic;

    @Test("QuantumSimulator")
    operation AllocateQubit () : Unit {
        
        using (q = Qubit()) {
            X(q); // the new line we added to make test fail
            Assert([PauliZ], [q], Zero, "Newly allocated qubit must be in |0> state."); //test fails here
        }
        
        Message("Test passed.");
    }
}

Then run dotnet test for the project and observe the following output:

[xUnit.net 00:00:01.12]     qsharp_unit_test_example.AllocateQubit+QuantumSimulator.AllocateQubit [FAIL]
  X qsharp_unit_test_example.AllocateQubit+QuantumSimulator.AllocateQubit [52ms]
  Error Message:
   System.AggregateException : One or more errors occurred. (Newly allocated qubit must be in |0> state.
        Expected:       0
        Actual: 1)
---- Microsoft.Quantum.Simulation.Core.ExecutionFailException : Newly allocated qubit must be in |0> state.
        Expected:       0
        Actual: 1
  Stack Trace:
     at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Threading.Tasks.Task.Wait()
   at qsharp_unit_test_example.AllocateQubit.QuantumSimulator.AllocateQubit() in D:\repos\qsharp-unit-test-example\Tests.qs:line 16
----- Inner Stack Trace -----
   at Microsoft.Quantum.Simulation.Simulators.QuantumSimulator.QSimAssert.<get_Body>b__6_0(ValueTuple`4 _args)
   at Microsoft.Quantum.Simulation.Core.Operation`2.Apply(I a)
   at Microsoft.Quantum.Simulation.Core.Operation`2.Microsoft.Quantum.Simulation.Core.ICallable<I,O>.Apply(I args)
   at qsharp_unit_test_example.AllocateQubit.<get_Body>b__27_0(QVoid __in__) in D:\repos\qsharp-unit-test-example\Tests.qs:line 13
--- End of stack trace from previous location where exception was thrown ---
   at qsharp_unit_test_example.AllocateQubit.<get_Body>b__27_0(QVoid __in__) in D:\repos\qsharp-unit-test-example\Tests.qs:line 14
   at Microsoft.Quantum.Simulation.Core.Operation`2.Apply(I a)
   at Microsoft.Quantum.Simulation.Core.Operation`2.Apply[GenO](Object args)
   at Microsoft.Quantum.Simulation.Common.SimulatorBase.Execute[T,I,O](I args)
   at Microsoft.Quantum.Simulation.Common.SimulatorBase.<>c__DisplayClass39_0`3.<Run>b__0()
   at System.Threading.Tasks.Task`1.InnerInvoke()
   at System.Threading.Tasks.Task.<>c.<.cctor>b__274_0(Object obj)
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state) 
--- End of stack trace from previous location where exception was thrown ---
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state) 
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
  Standard Output Messages:
 Unhandled exception. Microsoft.Quantum.Simulation.Core.ExecutionFailException: Newly allocated qubit must be in |0> state.
        Expected:       0
        Actual: 1
  ---> Microsoft.Quantum.Intrinsic.Assert on :line 13
    at qsharp_unit_test_example.AllocateQubit on D:\repos\qsharp-unit-test-example\Tests.qs:line 9

Potential solution

It would be nice if currently generated C# code in Tests.g.cs

public void AllocateQubit()
#line 9 "D:/repos/qsharp-unit-test-example/Tests.qs"
{
    var sim = new Microsoft.Quantum.Simulation.Simulators.QuantumSimulator();
    if (sim is Microsoft.Quantum.Simulation.Common.SimulatorBase baseSim && this.Output != null)
    {
        baseSim.OnLog += this.Output.WriteLine;
    }

    sim.Run<AllocateQubit, QVoid, QVoid>(QVoid.Instance).Wait();
    if (sim is IDisposable disposeSim)
    {
        disposeSim.Dispose();
    }
}

looked more like:

public void AllocateQubit()
#line 9 "D:/repos/qsharp-unit-test-example/Tests.qs"
{
    var sim = new Microsoft.Quantum.Simulation.Simulators.QuantumSimulator();
    if (sim is Microsoft.Quantum.Simulation.Common.SimulatorBase baseSim && this.Output != null)
    {
        baseSim.OnLog += this.Output.WriteLine;
    }
    try
    {
        sim.Execute<AllocateQubit, QVoid, QVoid>(QVoid.Instance);
    }
    catch(Exception e) 
    {
#line 9 "D:/repos/qsharp-unit-test-example/Tests.qs"        
        Xunit.Assert.True(false,"Q# Test failed. For details see the Standard output below.");
    }
    finally
    {
        if (sim is IDisposable disposeSim)
        {
            disposeSim.Dispose();
        }
    }
}

which leads to the following output upon test failure:

[xUnit.net 00:00:01.10]     qsharp_unit_test_example2.AllocateQubit+QuantumSimulator.AllocateQubit [FAIL]

  X qsharp_unit_test_example2.AllocateQubit+QuantumSimulator.AllocateQubit [51ms]
  Error Message:
   Q# Test failed. For details see the Standard Output Messages below.
Expected: True
Actual:   False
  Stack Trace:
     at qsharp_unit_test_example2.AllocateQubit.QuantumSimulator.AllocateQubit() in D:\repos\qsharp-unit-test-example\Tests.qs:line 9
  Standard Output Messages:
 Unhandled exception. Microsoft.Quantum.Simulation.Core.ExecutionFailException: Newly allocated qubit must be in |0> state.
        Expected:       0
        Actual: 1
  ---> Microsoft.Quantum.Intrinsic.Assert on :line 13
    at qsharp_unit_test_example.AllocateQubit on D:\repos\qsharp-unit-test-example\Tests.qs:line 9

Also note that with current code QuantumSimulator is not disposed in case exception happens.