ArgumentOrEnvironmentVariable overload without environment name prefix.

Cake.ArgumentHelpers.Tests/ArgumentOrEnvironmentVariableAliasTests.cs

@@ -105,6 +105,21 @@ namespace Cake.ArgumentHelpers.Tests
 			var expected = true;
 			var actual = cakeContextMock.Object.ArgumentOrEnvironmentVariable(testKey, testKeyEnvironmentPrefix, true);
 
+			Assert.AreEqual(expected, actual, "Didn't find Environment variable without prefix.");
+		}
+        [Test]
+        public void NullArgumentAndTrueEnvironmentNoPrefixOverload_ReturnsTrue()
+		{
+			var testKey = "someVariable";
+			var testKeyEnvironmentPrefix = (string)null;
+			bool? testArgumentValue = null;
+			bool? testEnvironmentValue = true;
+
+			SetupVariables(testKey, testKeyEnvironmentPrefix, testArgumentValue, testEnvironmentValue);
+
+			var expected = true;
+			var actual = cakeContextMock.Object.ArgumentOrEnvironmentVariable(testKey, true);
+
 			Assert.AreEqual(expected, actual, "Didn't find Environment variable without prefix.");
 		}
 		[Test]

Cake.ArgumentHelpers/ArgumentOrEnvironmentVariableAlias.cs

@@ -17,5 +17,15 @@ namespace Cake.ArgumentHelpers
         {
             return ArgumentAliases.Argument(context, name, EnvironmentAliases.EnvironmentVariable(context, (environmentNamePrefix ?? "") + name) ?? defaultValue.ToString()).Equals("true", StringComparison.OrdinalIgnoreCase);
         }
+
+		/// <summary>
+		/// Get a bool variable from various script inputs: first via Argument, then falling back on EnvironmentVariable, finally falling back on a default.
+		/// </summary>
+		/// <returns>Value found or default, first checked in command-line argument, then environment variable.</returns>
+		[CakeMethodAlias]
+		public static bool ArgumentOrEnvironmentVariable(this ICakeContext context, string name, bool defaultValue)
+		{
+            return context.ArgumentOrEnvironmentVariable(name, null, defaultValue);
+		}
     }
 }