Thursday, July 05, 2007

Evaluating Javascript in an NUnit test

Adam Esterline posted his solution to javascript testing. He uses WatiN to run tests, which I wasn't excited about; I was hoping for a way to test where I didn't have to install any more software anywhere. Here's the solution I came up with:

static object Evaluator(string code )

ICodeCompiler compiler;

compiler = new JScriptCodeProvider().CreateCompiler();
CompilerParameters parameters;

parameters = new CompilerParameters();
parameters.GenerateInMemory = true;
parameters.GenerateExecutable = true;


CompilerResults results;

results = compiler.CompileAssemblyFromSource(parameters, code);
if (results.Errors.Count > 0)
throw new Exception(results.Errors[0 ].ErrorText);

Assembly assembly = results.CompiledAssembly;

MethodInfo entryPoint = assembly.EntryPoint;

return entryPoint.Invoke(null, new object[] { null } );


public void EvaluatorTest()
Evaluator( "Context.Current.Data = \"Craig\"" );
Assert.AreEqual( "Craig", Context.Current.Data );

This seems elegant and able to handle a lot of things like side effects. Unfortunately I've been back on the server side for the most part and haven't really tried to put this code through its paces.