Add test for ExpectContinue with no content (dotnet#30065)

* Add test for ExpectContinue with no content

* Address PR feedback

src/System.Net.Http/tests/FunctionalTests/HttpClientHandlerTest.cs

@@ -1181,6 +1181,7 @@ await TestHelper.WhenAllCompletedOrAnyFailed(
  }
  }
 
+ [SkipOnTargetFramework(TargetFrameworkMonikers.NetFramework, "Doesn't send fragments")]
  [ActiveIssue(29802, TargetFrameworkMonikers.Uap)]
  [Theory]
  [InlineData("#origFragment", "", "#origFragment", false)]
@@ -1199,12 +1200,6 @@ public async Task GetAsync_AllowAutoRedirectTrue_RetainsOriginalFragmentIfApprop
  return;
  }
 
- if (IsNetfxHandler)
- {
- // Similarly, netfx doesn't send fragments at all.
- return;
- }
-
  if (IsWinHttpHandler)
  {
  // According to https://tools.ietf.org/html/rfc7231#section-7.1.2,
@@ -1893,15 +1888,10 @@ await LoopbackServer.CreateServerAsync(async (server, url) =>
  });
  }
 
+ [SkipOnTargetFramework(TargetFrameworkMonikers.NetFramework, "No exception thrown")]
  [Fact]
  public async Task SendAsync_TransferEncodingSetButNoRequestContent_Throws()
  {
- if (IsNetfxHandler)
- {
- // no exception thrown
- return;
- }
-
  var req = new HttpRequestMessage(HttpMethod.Post, "http://bing.com");
  req.Headers.TransferEncodingChunked = true;
  using (HttpClient c = CreateHttpClient())
@@ -2599,6 +2589,25 @@ public async Task PostAsync_ExpectContinue_Success(bool? expectContinue, string
  }
  }
 
+ [SkipOnTargetFramework(TargetFrameworkMonikers.NetFramework, "Doesn't send content for get requests")]
+ [ActiveIssue(29802, TargetFrameworkMonikers.Uap)]
+ [Fact]
+ public async Task GetAsync_ExpectContinueTrue_NoContent_StillSendsHeader()
+ {
+ await LoopbackServer.CreateClientAndServerAsync(async uri =>
+ {
+ using (var client = CreateHttpClient())
+ {
+ client.DefaultRequestHeaders.ExpectContinue = true;
+ await client.GetStringAsync(uri);
+ }
+ }, async server =>
+ {
+ List<string> headers = await server.AcceptConnectionSendResponseAndCloseAsync();
+ Assert.Contains("Expect: 100-continue", headers);
+ });
+ }
+
  [ActiveIssue(29802, TargetFrameworkMonikers.Uap)]
  [Theory]
  [InlineData(false)]