Add tests for OAuth2PushedAuthorizationRequestUri

Adds baseline test coverage for OAuth2PushedAuthorizationRequestUri,
which previously had none: a round-trip via create()/parse() and an
explicit parse() case on a hand-constructed request URI.

See gh-19444.

Signed-off-by: Josh Cummings <3627351+jzheaux@users.noreply.github.com>

oauth2/oauth2-authorization-server/src/test/java/org/springframework/security/oauth2/server/authorization/authentication/OAuth2PushedAuthorizationRequestUriTests.java

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2004-present the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.security.oauth2.server.authorization.authentication;
+
+import java.time.Instant;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link OAuth2PushedAuthorizationRequestUri}.
+ *
+ * @author Josh Cummings
+ */
+public class OAuth2PushedAuthorizationRequestUriTests {
+
+	@Test
+	public void parseWhenValidRequestUriThenReturnsExpectedValues() {
+		String state = "abcXYZ123-abcXYZ123";
+		long epochMilli = 1700000000000L;
+		String requestUri = "urn:ietf:params:oauth:request_uri:" + state + "___" + epochMilli;
+
+		OAuth2PushedAuthorizationRequestUri parsed = OAuth2PushedAuthorizationRequestUri.parse(requestUri);
+
+		assertThat(parsed.getRequestUri()).isEqualTo(requestUri);
+		assertThat(parsed.getState()).isEqualTo(state + "___" + epochMilli);
+		assertThat(parsed.getExpiresAt()).isEqualTo(Instant.ofEpochMilli(epochMilli));
+	}
+
+	@Test
+	public void createWhenParsedThenReturnsEquivalentValues() {
+		Instant expiresAt = Instant.ofEpochMilli(1700000000000L);
+
+		OAuth2PushedAuthorizationRequestUri created = OAuth2PushedAuthorizationRequestUri.create(expiresAt);
+		OAuth2PushedAuthorizationRequestUri parsed = OAuth2PushedAuthorizationRequestUri.parse(created.getRequestUri());
+
+		assertThat(parsed.getRequestUri()).isEqualTo(created.getRequestUri());
+		assertThat(parsed.getState()).isEqualTo(created.getState());
+		assertThat(parsed.getExpiresAt()).isEqualTo(created.getExpiresAt());
+	}
+
+}