Fix AdaptiveCapacityDictionary assert with 11 elements dotnet#34307

Author: Tratcher

src/Http/Http/src/Internal/RequestCookieCollection.cs

@@ -70,7 +70,9 @@ internal static RequestCookieCollection ParseInternal(StringValues values, bool
             {
                 return Empty;
             }
-            var collection = new RequestCookieCollection(values.Count);
+
+            // Do not set the collection capacity based on StringValues.Count, the Cookie header is supposed to be a single combine value.
+            var collection = new RequestCookieCollection();
             var store = collection.Store!;
 
             if (CookieHeaderParserShared.TryParseValues(values, store, enableCookieNameEncoding, supportsMultipleValues: true))

src/Http/Http/test/RequestCookiesCollectionTests.cs

@@ -38,5 +38,13 @@ public void AppContextSwitchUnEscapesKeysAndValues(string input, string expected
             Assert.Equal(expectedKey, cookies.Keys.Single());
             Assert.Equal(expectedValue, cookies[expectedKey]);
         }
+
+        [Fact]
+        public void ParseManyCookies()
+        {
+            var cookies = RequestCookieCollection.Parse(new StringValues(new[] { "a=a", "b=b", "c=c", "d=d", "e=e", "f=f", "g=g", "h=h", "i=i", "j=j", "k=k", "l=l" }));
+
+            Assert.Equal(12, cookies.Count);
+        }
     }
 }

src/Shared/Dictionary/AdaptiveCapacityDictionary.cs

@@ -77,7 +77,6 @@ public AdaptiveCapacityDictionary(int capacity, IEqualityComparer<TKey> comparer
             else
             {
                 _dictionaryStorage = new Dictionary<TKey, TValue>(capacity);
-                _arrayStorage = Array.Empty<KeyValuePair<TKey, TValue>>();
             }
         }
 
@@ -95,6 +94,7 @@ internal AdaptiveCapacityDictionary(IEnumerable<KeyValuePair<TKey, TValue>> valu
         {
             _comparer = comparer ?? EqualityComparer<TKey>.Default;
 
+            Debug.Assert(capacity <= DefaultArrayThreshold);
             _arrayStorage = new KeyValuePair<TKey, TValue>[capacity];
 
             foreach (var kvp in values)

src/Shared/test/Shared.Tests/AdaptiveCapacityDictionaryTests.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Globalization;
 using System.Linq;
 using Microsoft.AspNetCore.Internal;
 using Microsoft.AspNetCore.Testing;
@@ -100,6 +101,25 @@ public void CreateFromIEnumerableStringValuePair_CopiesValues()
                 kvp => { Assert.Equal("Middle Name", kvp.Key); Assert.Equal("Bob", kvp.Value); });
         }
 
+        [Fact]
+        public void CreateWithCapacityOverDefaultLimit()
+        {
+            // The default threshold between array and dictionary is 10. If we created one over that limit it should go directly to a dictionary.
+            var dict = new AdaptiveCapacityDictionary<string, string>(capacity: 12, StringComparer.OrdinalIgnoreCase);
+
+            Assert.Null(dict._arrayStorage);
+            Assert.NotNull(dict._dictionaryStorage);
+
+            for (var i = 0; i < 12; i++)
+            {
+                dict[i.ToString(CultureInfo.InvariantCulture)] = i.ToString(CultureInfo.InvariantCulture);
+            }
+
+            Assert.Null(dict._arrayStorage);
+            Assert.NotNull(dict._dictionaryStorage);
+            Assert.Equal(12, dict.Count);
+        }
+
         [Fact]
         public void CreateFromIEnumerableKeyValuePair_ThrowsExceptionForDuplicateKey()
         {