{"action":"created","comment":{"url":"https://api.github.com/repos/dotnet/corefx/pulls/comments/52116207","id":52116207,"diff_hunk":"@@ -0,0 +1,103 @@\n+// Licensed to the .NET Foundation under one or more agreements.\n+// The .NET Foundation licenses this file to you under the MIT license.\n+// See the LICENSE file in the project root for more information.\n+\n+using System;\n+using System.Collections.Generic;\n+using Xunit;\n+\n+namespace System.Linq.Tests\n+{\n+    public class AppendPrependTests : EnumerableTests\n+    {\n+        [Fact]\n+        public void SameResultsRepeatCallsIntQueryAppend()\n+        {\n+            var q1 = from x1 in new int?[] { 2, 3, null, 2, null, 4, 5 }\n+                     select x1;\n+                     \n+            Assert.Equal(q1.Append(42), q1.Append(42));\n+            Assert.Equal(q1.Append(42), q1.Concat(new int?[] { 42 }));\n+        }\n+\n+        [Fact]\n+        public void SameResultsRepeatCallsIntQueryPrepend()\n+        {\n+            var q1 = from x1 in new int?[] { 2, 3, null, 2, null, 4, 5 }\n+                     select x1;\n+\n+            Assert.Equal(q1.Prepend(42), q1.Prepend(42));\n+            Assert.Equal(q1.Prepend(42), (new int?[] { 42 }).Concat(q1));\n+        }\n+\n+        [Fact]\n+        public void SameResultsRepeatCallsStringQueryAppend()\n+        {\n+            var q1 = from x1 in new[] { \"AAA\", String.Empty, \"q\", \"C\", \"#\", \"!@#$%^\", \"0987654321\", \"Calling Twice\" }\n+                     select x1;\n+\n+            Assert.Equal(q1.Append(\"hi\"), q1.Append(\"hi\"));\n+            Assert.Equal(q1.Append(\"hi\"), q1.Concat(new string[] { \"hi\" }));\n+        }\n+\n+        [Fact]\n+        public void SameResultsRepeatCallsStringQueryPrepend()\n+        {\n+            var q1 = from x1 in new[] { \"AAA\", String.Empty, \"q\", \"C\", \"#\", \"!@#$%^\", \"0987654321\", \"Calling Twice\" }\n+                     select x1;\n+\n+            Assert.Equal(q1.Prepend(\"hi\"), q1.Prepend(\"hi\"));\n+            Assert.Equal(q1.Prepend(\"hi\"), (new string[] { \"hi\" }).Concat(q1));\n+        }\n+\n+        [Fact]\n+        public void EmptyAppend()\n+        {\n+            int[] first = { };\n+            Assert.Single(first.Append(42), 42);\n+        }\n+\n+        [Fact]\n+        public void EmptyPrepend()\n+        {\n+            string[] first = { };\n+            Assert.Single(first.Prepend(\"aa\"), \"aa\");\n+        }\n+\n+        [Fact]\n+        public void PrependNoIteratingSourceBeforeFirstItem()\n+        {\n+            var ie = new List<int>();\n+            var prepended = (from i in ie select i).Prepend(4);\n+\n+            ie.Add(42);\n+\n+            Assert.Equal(prepended, ie.Prepend(4));","path":"src/System.Linq/tests/AppendPrependTests.cs","position":75,"original_position":75,"commit_id":"bcd9f5d61e78afaebdf5da27ea5bff996a0b2b70","original_commit_id":"bcd9f5d61e78afaebdf5da27ea5bff996a0b2b70","user":{"login":"JonHanna","id":1253369,"avatar_url":"https://avatars.githubusercontent.com/u/1253369?v=3","gravatar_id":"","url":"https://api.github.com/users/JonHanna","html_url":"https://github.com/JonHanna","followers_url":"https://api.github.com/users/JonHanna/followers","following_url":"https://api.github.com/users/JonHanna/following{/other_user}","gists_url":"https://api.github.com/users/JonHanna/gists{/gist_id}","starred_url":"https://api.github.com/users/JonHanna/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/JonHanna/subscriptions","organizations_url":"https://api.github.com/users/JonHanna/orgs","repos_url":"https://api.github.com/users/JonHanna/repos","events_url":"https://api.github.com/users/JonHanna/events{/privacy}","received_events_url":"https://api.github.com/users/JonHanna/received_events","type":"User","site_admin":false},"body":"Maybe this test should assert that `GetEnumerator()` wasn't called prior to the second element being iterated. I can't see someone finding a way that iterating it had any advantage (quite the opposite), but eagerly calling `GetEnumerator()` might possibly profile as a slight improvement (or simply an implementation short-cut with less typing!), would have worse potential problems than this, and would cover everything this covers too.","created_at":"2016-02-07T11:43:53Z","updated_at":"2016-02-07T11:43:53Z","html_url":"https://github.com/dotnet/corefx/pull/5947#discussion_r52116207","pull_request_url":"https://api.github.com/repos/dotnet/corefx/pulls/5947","_links":{"self":{"href":"https://api.github.com/repos/dotnet/corefx/pulls/comments/52116207"},"html":{"href":"https://github.com/dotnet/corefx/pull/5947#discussion_r52116207"},"pull_request":{"href":"https://api.github.com/repos/dotnet/corefx/pulls/5947"}}},"pull_request":{"url":"https://api.github.com/repos/dotnet/corefx/pulls/5947","id":58532044,"html_url":"https://github.com/dotnet/corefx/pull/5947","diff_url":"https://github.com/dotnet/corefx/pull/5947.diff","patch_url":"https://github.com/dotnet/corefx/pull/5947.patch","issue_url":"https://api.github.com/repos/dotnet/corefx/issues/5947","number":5947,"state":"open","locked":false,"title":"Added   Enumerable.Append and Enumerable.Prepend","user":{"login":"VSadov","id":8218165,"avatar_url":"https://avatars.githubusercontent.com/u/8218165?v=3","gravatar_id":"","url":"https://api.github.com/users/VSadov","html_url":"https://github.com/VSadov","followers_url":"https://api.github.com/users/VSadov/followers","following_url":"https://api.github.com/users/VSadov/following{/other_user}","gists_url":"https://api.github.com/users/VSadov/gists{/gist_id}","starred_url":"https://api.github.com/users/VSadov/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/VSadov/subscriptions","organizations_url":"https://api.github.com/users/VSadov/orgs","repos_url":"https://api.github.com/users/VSadov/repos","events_url":"https://api.github.com/users/VSadov/events{/privacy}","received_events_url":"https://api.github.com/users/VSadov/received_events","type":"User","site_admin":false},"body":"New public API in System.Linq\r\n\r\nCloses #2075","created_at":"2016-02-06T22:19:42Z","updated_at":"2016-02-07T11:43:53Z","closed_at":null,"merged_at":null,"merge_commit_sha":"9d8d2b4abfa261c0412bb1535e50311692f7fab3","assignee":null,"milestone":null,"commits_url":"https://api.github.com/repos/dotnet/corefx/pulls/5947/commits","review_comments_url":"https://api.github.com/repos/dotnet/corefx/pulls/5947/comments","review_comment_url":"https://api.github.com/repos/dotnet/corefx/pulls/comments{/number}","comments_url":"https://api.github.com/repos/dotnet/corefx/issues/5947/comments","statuses_url":"https://api.github.com/repos/dotnet/corefx/statuses/bcd9f5d61e78afaebdf5da27ea5bff996a0b2b70","head":{"label":"VSadov:prepend","ref":"prepend","sha":"bcd9f5d61e78afaebdf5da27ea5bff996a0b2b70","user":{"login":"VSadov","id":8218165,"avatar_url":"https://avatars.githubusercontent.com/u/8218165?v=3","gravatar_id":"","url":"https://api.github.com/users/VSadov","html_url":"https://github.com/VSadov","followers_url":"https://api.github.com/users/VSadov/followers","following_url":"https://api.github.com/users/VSadov/following{/other_user}","gists_url":"https://api.github.com/users/VSadov/gists{/gist_id}","starred_url":"https://api.github.com/users/VSadov/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/VSadov/subscriptions","organizations_url":"https://api.github.com/users/VSadov/orgs","repos_url":"https://api.github.com/users/VSadov/repos","events_url":"https://api.github.com/users/VSadov/events{/privacy}","received_events_url":"https://api.github.com/users/VSadov/received_events","type":"User","site_admin":false},"repo":{"id":36833840,"name":"corefx","full_name":"VSadov/corefx","owner":{"login":"VSadov","id":8218165,"avatar_url":"https://avatars.githubusercontent.com/u/8218165?v=3","gravatar_id":"","url":"https://api.github.com/users/VSadov","html_url":"https://github.com/VSadov","followers_url":"https://api.github.com/users/VSadov/followers","following_url":"https://api.github.com/users/VSadov/following{/other_user}","gists_url":"https://api.github.com/users/VSadov/gists{/gist_id}","starred_url":"https://api.github.com/users/VSadov/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/VSadov/subscriptions","organizations_url":"https://api.github.com/users/VSadov/orgs","repos_url":"https://api.github.com/users/VSadov/repos","events_url":"https://api.github.com/users/VSadov/events{/privacy}","received_events_url":"https://api.github.com/users/VSadov/received_events","type":"User","site_admin":false},"private":false,"html_url":"https://github.com/VSadov/corefx","description":"This repo contains the .NET Core foundational libraries, called CoreFX. 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