TEST_P(HeaderIntegrationTest, TestAppendSameHeaders) {
  initializeFilter(HeaderMode::Append, false);
  performRequest(
      Http::TestRequestHeaderMapImpl{
          {":method", "GET"},
          {":path", "/test"},
          {":scheme", "http"},
          {":authority", "append-same-headers.com"},
          {"user-agent", "token3"},
          {"x-foo", "value3"},
      },
      Http::TestRequestHeaderMapImpl{
          {":authority", "append-same-headers.com"},
          {":path", "/test"},
          {":method", "GET"},
          {"user-agent", "token3,token2,token1"},
          {"x-foo", "value3"},
          {"x-foo", "value2"},
          {"x-foo", "value1"},
      },
      Http::TestResponseHeaderMapImpl{
          {"server", "envoy"},
          {"content-length", "0"},
          {":status", "200"},
          {"x-unmodified", "response"},
      },
      Http::TestResponseHeaderMapImpl{
          {"server", "envoy"},
          {"x-unmodified", "response"},
          {":status", "200"},
      });
}
TEST_P(HeaderIntegrationTest, TestAppendSameHeaders) {
  initializeFilter(HeaderMode::Append, false);
  performRequest(
      Http::TestRequestHeaderMapImpl{
          {":method", "GET"},
          {":path", "/test"},
          {":scheme", "http"},
          {":authority", "append-same-headers.com"},
          {"user-agent", "token3"},
          {"x-foo", "value3"},
      },
      Http::TestRequestHeaderMapImpl{
          {":authority", "append-same-headers.com"},
          {":path", "/test"},
          {":method", "GET"},
          {"user-agent", "token3,token2,token1"},
          {"x-foo", "value3"},
          {"x-foo", "value2"},
          {"x-foo", "value1"},
      },
      Http::TestResponseHeaderMapImpl{
          {"server", "envoy"},
          {"content-length", "0"},
          {":status", "200"},
          {"x-unmodified", "response"},
      },
      Http::TestResponseHeaderMapImpl{
          {"server", "envoy"},
          {"x-unmodified", "response"},
          {":status", "200"},
      });
}