Fix tests.

Author: ManickaP

src/libraries/Common/tests/System/Net/Http/GenericLoopbackServer.cs

@@ -258,6 +258,24 @@ public static async Task<HttpRequestData> FromHttpRequestMessageAsync(System.Net
             return result;
         }
 
+        public HttpHeaderData[] GetHeaderData(string headerName)
+        {
+            return Headers.Where(h => h.Name.Equals(headerName, StringComparison.OrdinalIgnoreCase)).ToArray();
+        }
+
+        public HttpHeaderData GetSingleHeaderData(string headerName)
+        {
+            HttpHeaderData[] data = GetHeaderData(headerName);
+            if (data.Length != 1)
+            {
+                throw new Exception(
+                    $"Expected single value for {headerName} header, actual count: {data.Length}{Environment.NewLine}" +
+                    $"{"\t"}{string.Join(Environment.NewLine + "\t", data)}");
+            }
+
+            return data[0];
+        }
+
         public string[] GetHeaderValues(string headerName)
         {
             return Headers.Where(h => h.Name.Equals(headerName, StringComparison.OrdinalIgnoreCase))

src/libraries/Common/tests/System/Net/Http/HttpClientHandlerTest.cs

@@ -2283,23 +2283,30 @@ await LoopbackServerFactory.CreateClientAndServerAsync(async uri =>
                 }, async server =>
                 {
                     var data = await server.AcceptConnectionSendResponseAndCloseAsync();
-                    var expectedValue = headerValue;
-                    if (safeChar > 0x7F)
-                    {
-                        Assert.True(IsWinHttpHandler);
-                        expectedValue = headerValue.Replace(safeChar, '?'); // WinHttpHandler replaces Latin-1 characters with '?'.
-                    }
+                    var encoding = Encoding.GetEncoding("ISO-8859-1");
                     switch (headerType)
                     {
                         case HeaderType.Request:
-                            Assert.Equal(expectedValue, data.GetSingleHeaderValue("Custom-Header"));
+                        {
+                            var headerLine = encoding.GetString(data.GetSingleHeaderData("Custom-Header").Raw);
+                            var receivedHeaderValue = headerLine.Substring(headerLine.IndexOf(':') + 1).TrimStart();
+                            Assert.Equal(headerValue, receivedHeaderValue);
                             break;
+                        }
                         case HeaderType.Content:
-                            Assert.Equal(expectedValue, data.GetSingleHeaderValue("Custom-Content-Header"));
+                        {
+                            var headerLine = encoding.GetString(data.GetSingleHeaderData("Custom-Content-Header").Raw);
+                            var receivedHeaderValue = headerLine.Substring(headerLine.IndexOf(':') + 1).TrimStart();
+                            Assert.Equal(headerValue, receivedHeaderValue);
                             break;
+                        }
                         case HeaderType.Cookie:
-                            Assert.Equal($"CustomCookie={expectedValue}", data.GetSingleHeaderValue("cookie"));
+                        {
+                            var headerLine = encoding.GetString(data.GetSingleHeaderData("cookie").Raw);
+                            var receivedHeaderValue = headerLine.Substring(headerLine.IndexOf(':') + 1).TrimStart();
+                            Assert.Equal($"CustomCookie={headerValue}", receivedHeaderValue);
                             break;
+                        }
                     }
                 });
         }