JimEvans: Introduces the Updating the CustomFinderType property to th…

…e .NET FindsByAttribute. This allows use of custom By subclasses in the PageFactory. The custom finder must be a subclass of By, and it must expose a public constructor that takes a string argument. To use a custom finder with the FindsByAttribute, use the following syntax:

[FindsBy(How = How.Custom, Using = "customCriteria", CustomFinderType = typeof(MyCustomBySubclass))]

Using How.Custom without specifying a CustomFinderType, or using a CustomFinderType that either does not descend from By or does not have a proper constructor will throw an exception.

Fixes issue SeleniumHQ#4878

r18291

dotnet/src/WebDriver.Support/PageObjects/ByFactory.cs

@@ -18,6 +18,7 @@
 
 using System;
 using System.Globalization;
+using System.Reflection;
 
 namespace OpenQA.Selenium.Support.PageObjects
 {
@@ -53,6 +54,25 @@ public static By From(FindsByAttribute attribute)
                     return By.PartialLinkText(usingValue);
                 case How.XPath:
                     return By.XPath(usingValue);
+                case How.Custom:
+                    if (attribute.CustomFinderType == null)
+                    {
+                        throw new ArgumentException("Cannot use How.Custom without supplying a custom finder type");
+                    }
+
+                    if (!attribute.CustomFinderType.IsSubclassOf(typeof(By)))
+                    {
+                        throw new ArgumentException("Custom finder type must be a descendent of the By class");
+                    }
+
+                    ConstructorInfo ctor = attribute.CustomFinderType.GetConstructor(new Type[] { typeof(string) });
+                    if (ctor == null)
+                    {
+                        throw new ArgumentException("Custom finder type must expose a public constructor with a string argument");
+                    }
+
+                    By finder = ctor.Invoke(new object[] { usingValue }) as By;
+                    return finder;
             }
 
             throw new ArgumentException(string.Format(CultureInfo.InvariantCulture, "Did not know how to construct How from how {0}, using {1}", how, usingValue));

dotnet/src/WebDriver.Support/PageObjects/FindsByAttribute.cs

@@ -48,6 +48,13 @@ public sealed class FindsByAttribute : Attribute, IComparable
         [DefaultValue(0)]
         public int Priority { get; set; }
 
+        /// <summary>
+        /// Gets or sets a value indicating the <see cref="Type"/> of the custom finder. The custom finder must
+        /// descend from the <see cref="By"/> class, and expose a public constructor that takes a <see cref="String"/>
+        /// argument.
+        /// </summary>
+        public Type CustomFinderType { get; set; }
+
         /// <summary>
         /// Gets or sets an explicit <see cref="By"/> object to find by.
         /// Setting this property takes precedence over setting the How or Using properties.
@@ -135,9 +142,9 @@ internal By Finder
         /// <returns>A value that indicates the relative order of the objects being compared. The return value has these meanings:
         /// <list type="table">
         /// <listheader>Value</listheader><listheader>Meaning</listheader>
-        /// <item><description>Less than zero</description><description>This instance precedes obj in the sort order.</description></item>
-        /// <item><description>Zero</description><description>This instance occurs in the same position in the sort order as obj.</description></item>
-        /// <item><description>Greater than zero</description><description>This instance follows obj in the sort order. </description></item>
+        /// <item><description>Less than zero</description><description>This instance precedes <paramref name="obj"/> in the sort order.</description></item>
+        /// <item><description>Zero</description><description>This instance occurs in the same position in the sort order as <paramref name="obj"/>.</description></item>
+        /// <item><description>Greater than zero</description><description>This instance follows <paramref name="obj"/> in the sort order. </description></item>
         /// </list>
         /// </returns>
         public int CompareTo(object obj)

dotnet/src/WebDriver.Support/PageObjects/How.cs

@@ -61,6 +61,11 @@ public enum How
         /// <summary>
         /// Finds by <see cref="OpenQA.Selenium.By.XPath" />
         /// </summary>
-        XPath
+        XPath,
+
+        /// <summary>
+        /// Finds by a custom <see cref="By"/> implementation.
+        /// </summary>
+        Custom
     }
 }

dotnet/test/WebDriver.Support.Tests/PageObjects/PageFactoryTest.cs

@@ -170,6 +170,51 @@ public void CachesIfClassMarkedCachedElement()
             AssertFoundElement(page.formElement);
         }
 
+        [Test]
+        public void UsingCustomBy()
+        {
+            Expect.Exactly(1).On(mockDriver).Method("FindElement").With(new CustomBy("customCriteria")).Will(Return.Value(mockElement));
+            Expect.Exactly(1).On(mockElement).GetProperty("TagName").Will(Return.Value("form"));
+
+            var page = new CustomByPage();
+
+            AssertFindsElement(page, () => page.customFoundElement);
+        }
+
+        [Test]
+        public void UsingCustomByNotFound()
+        {
+            Expect.Once.On(mockDriver).Method("FindElement").With(new CustomBy("customCriteriaNotFound")).Will(Throw.Exception(new NoSuchElementException()));
+
+            var page = new CustomByNotFoundPage();
+            PageFactory.InitElements(mockDriver, page);
+            Assert.Throws(typeof(NoSuchElementException), page.customFoundElement.Clear);
+        }
+
+        [Test]
+        [ExpectedException(typeof(ArgumentException), ExpectedMessage = "descendent of", MatchType = MessageMatch.Contains)]
+        public void UsingCustomByWithInvalidSuperClass()
+        {
+            var page = new InvalidCustomFinderTypePage();
+            PageFactory.InitElements(mockDriver, page);
+        }
+
+        [Test]
+        [ExpectedException(typeof(ArgumentException), ExpectedMessage = "How.Custom", MatchType = MessageMatch.Contains)]
+        public void UsingCustomByWithNoClass()
+        {
+            var page = new NoCustomFinderClassPage();
+            PageFactory.InitElements(mockDriver, page);
+        }
+
+        [Test]
+        [ExpectedException(typeof(ArgumentException), ExpectedMessage = "constructor", MatchType = MessageMatch.Contains)]
+        public void UsingCustomByWithInvalidCtor()
+        {
+            var page = new InvalidCtorCustomByPage();
+            PageFactory.InitElements(mockDriver, page);
+        }
+
         #region Test helper methods
 
         private void ExpectOneLookup()
@@ -305,6 +350,78 @@ private class CachedClassPage
             public IWebElement formElement;
         }
 
+        private class CustomBy : By
+        {
+            Mockery mocks = new Mockery();
+            private string criteria;
+
+            public CustomBy(string customByString)
+            {
+                criteria = customByString;
+                this.FindElementMethod = (context) =>
+                {
+                    if (this.criteria != "customCriteria")
+                    {
+                        throw new NoSuchElementException();
+                    }
+
+                    IWebElement mockElement =  mocks.NewMock<IWebElement>();
+                    return mockElement;
+                };
+            }
+        }
+
+        private class CustomByNoCtor : By
+        {
+            Mockery mocks = new Mockery();
+            private string criteria;
+
+            public CustomByNoCtor()
+            {
+                criteria = "customCriteria";
+                this.FindElementMethod = (context) =>
+                {
+                    if (this.criteria != "customCriteria")
+                    {
+                        throw new NoSuchElementException();
+                    }
+
+                    IWebElement mockElement =  mocks.NewMock<IWebElement>();
+                    return mockElement;
+                };
+            }
+        }
+
+        private class CustomByPage
+        {
+            [FindsBy(How = How.Custom, Using = "customCriteria", CustomFinderType = typeof(CustomBy))]
+            public IWebElement customFoundElement;
+        }
+
+        private class CustomByNotFoundPage
+        {
+            [FindsBy(How = How.Custom, Using = "customCriteriaNotFound", CustomFinderType = typeof(CustomBy))]
+            public IWebElement customFoundElement;
+        }
+
+        private class NoCustomFinderClassPage
+        {
+            [FindsBy(How = How.Custom, Using = "custom")]
+            public IWebElement customFoundElement;
+        }
+
+        private class InvalidCustomFinderTypePage
+        {
+            [FindsBy(How = How.Custom, Using = "custom", CustomFinderType = typeof(string))]
+            public IWebElement customFoundElement;
+        }
+
+        private class InvalidCtorCustomByPage
+        {
+            [FindsBy(How = How.Custom, Using = "custom", CustomFinderType = typeof(CustomByNoCtor))]
+            public IWebElement customFoundElement;
+        }
+
         #pragma warning restore 649
         #endregion
     }