ps.ipam/classlib.tests/Mocks/CmdletTestHelper.cs

namespace PS.IPAM.Tests.Mocks;

using System.Management.Automation;
using System.Management.Automation.Host;
using System.Reflection;

/// <summary>
/// Helper class for testing PowerShell cmdlets.
/// </summary>
public class CmdletTestHelper<T> : IDisposable where T : PSCmdlet, new()
{
    private readonly T _cmdlet;
    private readonly List<object> _output = new();
    private readonly List<ErrorRecord> _errors = new();
    private bool _disposed;

    public CmdletTestHelper()
    {
        _cmdlet = new T();
    }

    /// <summary>
    /// Gets the cmdlet instance for setting parameters.
    /// </summary>
    public T Cmdlet => _cmdlet;

    /// <summary>
    /// Gets the output objects written by the cmdlet.
    /// </summary>
    public IReadOnlyList<object> Output => _output.AsReadOnly();

    /// <summary>
    /// Gets the errors written by the cmdlet.
    /// </summary>
    public IReadOnlyList<ErrorRecord> Errors => _errors.AsReadOnly();

    /// <summary>
    /// Gets whether any errors were written.
    /// </summary>
    public bool HasErrors => _errors.Count > 0;

    /// <summary>
    /// Invokes the cmdlet and captures output.
    /// </summary>
    public void Invoke()
    {
        // Use reflection to call the protected ProcessRecord method
        var processMethod = typeof(T).GetMethod("ProcessRecord",
            BindingFlags.NonPublic | BindingFlags.Instance);

        if (processMethod == null)
        {
            throw new InvalidOperationException("ProcessRecord method not found on cmdlet.");
        }

        // Set up a mock command runtime to capture output
        var runtime = new MockCommandRuntime(_output, _errors);
        var runtimeProperty = typeof(Cmdlet).GetProperty("CommandRuntime",
            BindingFlags.Public | BindingFlags.Instance);

        runtimeProperty?.SetValue(_cmdlet, runtime);

        // Invoke the method
        try
        {
            processMethod.Invoke(_cmdlet, null);
        }
        catch (TargetInvocationException ex) when (ex.InnerException != null)
        {
            // Unwrap the exception
            throw ex.InnerException;
        }
    }

    public void Dispose()
    {
        if (!_disposed)
        {
            _disposed = true;
        }
    }
}

/// <summary>
/// Mock implementation of ICommandRuntime for capturing cmdlet output.
/// This is a minimal implementation that only handles the methods we need for testing.
/// </summary>
internal class MockCommandRuntime : ICommandRuntime
{
    private readonly List<object> _output;
    private readonly List<ErrorRecord> _errors;

    public MockCommandRuntime(List<object> output, List<ErrorRecord> errors)
    {
        _output = output;
        _errors = errors;
    }

    public PSHost Host => null!;
    public PSTransactionContext CurrentPSTransaction => null!;

    public bool ShouldContinue(string query, string caption) => true;
    public bool ShouldContinue(string query, string caption, ref bool yesToAll, ref bool noToAll) => true;
    public bool ShouldProcess(string target) => true;
    public bool ShouldProcess(string target, string action) => true;
    public bool ShouldProcess(string verboseDescription, string verboseWarning, string caption) => true;
    public bool ShouldProcess(string verboseDescription, string verboseWarning, string caption, out ShouldProcessReason shouldProcessReason)
    {
        shouldProcessReason = ShouldProcessReason.None;
        return true;
    }

    public bool TransactionAvailable() => false;

    public void ThrowTerminatingError(ErrorRecord errorRecord) => throw errorRecord.Exception;

    public void WriteCommandDetail(string text) { }
    public void WriteDebug(string text) { }
    public void WriteError(ErrorRecord errorRecord) => _errors.Add(errorRecord);
    public void WriteObject(object sendToPipeline) => _output.Add(sendToPipeline);
    public void WriteObject(object sendToPipeline, bool enumerateCollection)
    {
        if (enumerateCollection && sendToPipeline is System.Collections.IEnumerable enumerable)
        {
            foreach (var item in enumerable)
            {
                _output.Add(item);
            }
        }
        else
        {
            _output.Add(sendToPipeline);
        }
    }
    public void WriteProgress(ProgressRecord progressRecord) { }
    public void WriteProgress(long sourceId, ProgressRecord progressRecord) { }
    public void WriteVerbose(string text) { }
    public void WriteWarning(string text) { }
}