test: fix broken tests

tests/HuskyTest/Cli/ExecCommandTests.cs

@@ -1,7 +1,7 @@
 using System.Collections.Immutable;
 using System.IO.Abstractions;
+using System.IO.Abstractions.TestingHelpers;
 using System.Reflection;
-using System.Text;
 using CliFx.Exceptions;
 using CliFx.Infrastructure;
 using FluentAssertions;
@@ -145,13 +145,15 @@ public async Task Exec_CachedScript_ShouldThrowWithNonZeroExitCode()
          const string filePath = "fake_file.csx";
          const string stringContent = @"
                return 1;
-            ";
+         ";
+
          _io.Path.GetDirectoryName(Arg.Any<string>()).Returns(Directory.GetCurrentDirectory());
          _io.File.Exists(Arg.Any<string>()).Returns(true);
          _io.Directory.Exists(Arg.Any<string>()).Returns(true);
          _io.File.ReadAllTextAsync(Arg.Any<string>()).Returns(stringContent);
-         await using var stream = new MemoryStream(Encoding.UTF8.GetBytes(stringContent));
-         _io.FileStream.Create(Arg.Any<string>(), FileMode.Open).Returns(stream);
+
+         var mockFileSystem = new MockFileSystem(new Dictionary<string, MockFileData> { { filePath, new MockFileData(stringContent) } });
+         _io.FileStream.New(filePath, FileMode.Open).Returns(mockFileSystem.File.Create(filePath));
 
          var opts = ScriptOptions.Default
             .WithSourceResolver(new SourceFileResolver(ImmutableArray<string>.Empty, null))
@@ -160,7 +162,7 @@ public async Task Exec_CachedScript_ShouldThrowWithNonZeroExitCode()
          var compilation = script.GetCompilation();
 
          await using var assemblyStream = new MemoryStream();
-         var _ = compilation.Emit(assemblyStream);
+         _ = compilation.Emit(assemblyStream);
          _assembly.LoadFile(Arg.Any<string>()).Returns(Assembly.Load(assemblyStream.ToArray()));
 
          var command = new ExecCommand(_io, _git, _assembly) { Path = filePath, Arguments = new List<string> { "test" }, NoCache = false };