Add test for default return value of QuicSpdySession::server_push_enabled().

This is a follow-up to cl/301242145.

gfe-relnote: n/a, test-only change.
PiperOrigin-RevId: 301366225
Change-Id: I92cbfcb6c483757a43046bd42420fd30168a8378

quic/core/http/quic_spdy_session_test.cc

diff --git a/quic/core/http/quic_spdy_session_test.cc b/quic/core/http/quic_spdy_session_test.cc
index 408b0fa..caca24c 100644
--- a/quic/core/http/quic_spdy_session_test.cc
+++ b/quic/core/http/quic_spdy_session_test.cc
@@ -2802,6 +2802,14 @@
   session_.OnHttp3GoAway(stream_id);
 }
 
+TEST_P(QuicSpdySessionTestServer, ServerPushEnabledDefaultValue) {
+  if (VersionUsesHttp3(transport_version())) {
+    EXPECT_FALSE(session_.server_push_enabled());
+  } else {
+    EXPECT_TRUE(session_.server_push_enabled());
+  }
+}
+
 TEST_P(QuicSpdySessionTestServer, OnSetting) {
   MockPacketWriter* writer = static_cast<MockPacketWriter*>(
       QuicConnectionPeer::GetWriter(session_.connection()));