Implement Page.QuerySelectorAllHandleAsync(..). EvaluateFunctionAsync() (a.k.a. Page.$$eval) (#198)

Author: Meir017

lib/PuppeteerSharp.Tests/Page/EvalManyTests.cs

@@ -0,0 +1,17 @@
+using System.Threading.Tasks;
+using Xunit;
+
+namespace PuppeteerSharp.Tests.Page
+{
+    [Collection("PuppeteerLoaderFixture collection")]
+    public class EvalManyTests : PuppeteerPageBaseTest
+    {
+        [Fact]
+        public async Task ShouldWork()
+        {
+            await Page.SetContentAsync("<div>hello</div><div>beautiful</div><div>world!</div>");
+            var divsCount = await Page.QuerySelectorAllHandleAsync("div").EvaluateFunctionAsync<int>("divs => divs.length");
+            Assert.Equal(3, divsCount);
+        }
+    }
+}

lib/PuppeteerSharp/Extensions.cs

@@ -24,9 +24,29 @@ public static async Task<T> EvaluateFunctionAsync<T>(this Task<ElementHandle> el
             var newArgs = new object[args.Length + 1];
             newArgs[0] = elementHandle;
             args.CopyTo(newArgs, 1);
-            var result = await elementHandle.Page.EvaluateFunctionAsync<T>(pageFunction, newArgs);
+            var result = await elementHandle.ExecutionContext.EvaluateFunctionAsync<T>(pageFunction, newArgs);
             await elementHandle.DisposeAsync();
             return result;
         }
+
+        /// <summary>
+        /// Runs <paramref name="pageFunction"/> within the frame and passes it the outcome of <paramref name="arrayHandleTask"/> as the first argument. Use only after <see cref="Page.QuerySelectorAllHandleAsync(string)"/>
+        /// </summary>
+        /// <typeparam name="T"></typeparam>
+        /// <param name="arrayHandleTask">A task that returns an <see cref="JSHandle"/> that represents an array of <see cref="ElementHandle"/> that will be used as the first argument in <paramref name="pageFunction"/></param>
+        /// <param name="pageFunction">Function to be evaluated in browser context</param>
+        /// <param name="args">Arguments to pass to <c>pageFunction</c></param>
+        /// <returns>Task which resolves to the return value of <c>pageFunction</c></returns>
+        public static async Task<T> EvaluateFunctionAsync<T>(this Task<JSHandle> arrayHandleTask, string pageFunction, params object[] args)
+        {
+            var arrayHandle = await arrayHandleTask;
+            
+            var newArgs = new object[args.Length + 1];
+            newArgs[0] = arrayHandle;
+            args.CopyTo(newArgs, 1);
+            var result = await arrayHandle.ExecutionContext.EvaluateFunctionAsync<T>(pageFunction, newArgs);
+            await arrayHandle.DisposeAsync();
+            return result;
+        }
     }
 }

lib/PuppeteerSharp/Page.cs

@@ -169,16 +169,24 @@ public async Task TapAsync(string selector)
         /// <remarks>
         /// Shortcut for <c>page.MainFrame.QuerySelectorAsync(selector)</c>
         /// </remarks>
-        public async Task<ElementHandle> QuerySelectorAsync(string selector)
-            => await MainFrame.QuerySelectorAsync(selector);
+        public Task<ElementHandle> QuerySelectorAsync(string selector)
+            => MainFrame.QuerySelectorAsync(selector);
 
         /// <summary>
         /// Runs <c>document.querySelectorAll</c> within the page. If no elements match the selector, the return value resolve to <see cref="Array.Empty{T}"/>.
         /// </summary>
         /// <param name="selector">A selector to query page for</param>
         /// <returns>Task which resolves to ElementHandles pointing to the frame elements</returns>
-        public async Task<ElementHandle[]> QuerySelectorAllAsync(string selector)
-            => await MainFrame.QuerySelectorAllAsync(selector);
+        public Task<ElementHandle[]> QuerySelectorAllAsync(string selector)
+            => MainFrame.QuerySelectorAllAsync(selector);
+
+        /// <summary>
+        /// A utility function to based used with <see cref="Extensions.EvaluateFunctionAsync{T}(Task{JSHandle}, string, object[])"/>
+        /// </summary>
+        /// <param name="selector">A selector to query page for</param>
+        /// <returns>Task which resolves to a <see cref="JSHandle"/> of <c>document.querySelectorAll</c> result</returns>
+        public Task<JSHandle> QuerySelectorAllHandleAsync(string selector)
+            => EvaluateFunctionHandleAsync("selector => Array.from(document.querySelectorAll(selector))", selector);
 
         /// <summary>
         /// Executes a script in browser context