Enhance check for value types to exclude Nullable

The System.Nullable type is a value type that can be assigned the null value. This change checks for types wrapped with Nullable and does not throw when they are encountered. Fixes SeleniumHQ#1316 Signed-off-by: Jim Evans <james.h.evans.jr@gmail.com>

Author: chrisblock

dotnet/src/support/Extensions/WebDriverExtensions.cs

@@ -91,7 +91,7 @@ public static T ExecuteJavaScript<T>(this IWebDriver driver, string script, para
  object value = executor.ExecuteScript(script, args);
  if (value == null)
  {
- if (type.IsValueType)
+ if (type.IsValueType && (Nullable.GetUnderlyingType(type) == null))
  {
  throw new WebDriverException("Script returned null, but desired type is a value type");
  }

dotnet/test/support/Extensions/ExecuteJavaScriptTest.cs

@@ -112,6 +112,17 @@ public void ShouldNotThrowWhenNullIsReturned()
  Assert.That(() => driver.ExecuteJavaScript<string>(JavaScript, JavaScriptParameters), Throws.Nothing);
  }
 
+ [Test]
+ public void ShouldNotThrowWhenNullIsReturnedForNullableValueType()
+ {
+ Expect.Once.On(driver)
+ .Method("ExecuteScript")
+ .With(JavaScript, JavaScriptParameters)
+ .Will(Return.Value(null));
+
+ Assert.That(() => driver.ExecuteJavaScript<int?>(JavaScript, JavaScriptParameters), Throws.Nothing);
+ }
+
  [Test]
  public void ShouldThrowWhenNullIsReturnedForValueType()
  {