test: Add test coverage for ChatClientObservationContext (#4124)

Signed-off-by: Oleksandr Klymenko <[email protected]>

Author: alxkm

spring-ai-client-chat/src/test/java/org/springframework/ai/chat/client/observation/ChatClientObservationContextTests.java

@@ -74,4 +74,114 @@ void whenAdvisorsWithNullElementsThenReturn() {
 			.hasMessageContaining("advisors cannot contain null elements");
 	}
 
+	@Test
+	void whenNullRequestThenThrowException() {
+		assertThatThrownBy(() -> ChatClientObservationContext.builder().request(null).build())
+			.isInstanceOf(IllegalArgumentException.class);
+	}
+
+	@Test
+	void whenValidAdvisorsListThenReturn() {
+		List<Advisor> advisors = List.of(mock(Advisor.class), mock(Advisor.class));
+
+		var observationContext = ChatClientObservationContext.builder()
+			.request(ChatClientRequest.builder().prompt(new Prompt()).build())
+			.advisors(advisors)
+			.build();
+
+		assertThat(observationContext).isNotNull();
+		assertThat(observationContext.getAdvisors()).hasSize(2);
+		// Check that advisors are present, but don't assume exact ordering or same
+		// instances
+		assertThat(observationContext.getAdvisors()).isNotNull().isNotEmpty();
+	}
+
+	@Test
+	void whenAdvisorsModifiedAfterBuildThenContextMayBeUnaffected() {
+		List<Advisor> advisors = new ArrayList<>();
+		advisors.add(mock(Advisor.class));
+
+		var observationContext = ChatClientObservationContext.builder()
+			.request(ChatClientRequest.builder().prompt(new Prompt()).build())
+			.advisors(advisors)
+			.build();
+
+		int originalSize = observationContext.getAdvisors().size();
+
+		// Try to modify original list
+		advisors.add(mock(Advisor.class));
+
+		// Check if context is affected or not - both are valid implementations
+		int currentSize = observationContext.getAdvisors().size();
+		// Defensive copy was made
+		// Same reference used
+		assertThat(currentSize).satisfiesAnyOf(size -> assertThat(size).isEqualTo(originalSize),
+				size -> assertThat(size).isEqualTo(originalSize + 1));
+	}
+
+	@Test
+	void whenGetAdvisorsCalledThenReturnsValidCollection() {
+		List<Advisor> advisors = List.of(mock(Advisor.class));
+
+		var observationContext = ChatClientObservationContext.builder()
+			.request(ChatClientRequest.builder().prompt(new Prompt()).build())
+			.advisors(advisors)
+			.build();
+
+		var returnedAdvisors = observationContext.getAdvisors();
+
+		// Just verify we get a valid collection back, using var to handle any return type
+		assertThat(returnedAdvisors).isNotNull();
+		assertThat(returnedAdvisors).hasSize(1);
+	}
+
+	@Test
+	void whenRequestWithNullPromptThenThrowException() {
+		assertThatThrownBy(() -> ChatClientRequest.builder().prompt(null).build())
+			.isInstanceOf(IllegalArgumentException.class);
+	}
+
+	@Test
+	void whenEmptyAdvisorsListThenReturn() {
+		var observationContext = ChatClientObservationContext.builder()
+			.request(ChatClientRequest.builder().prompt(new Prompt()).build())
+			.advisors(List.of())
+			.build();
+
+		assertThat(observationContext).isNotNull();
+		assertThat(observationContext.getAdvisors()).isEmpty();
+	}
+
+	@Test
+	void whenGetRequestThenReturnsSameInstance() {
+		ChatClientRequest request = ChatClientRequest.builder().prompt(new Prompt("Test prompt")).build();
+
+		var observationContext = ChatClientObservationContext.builder().request(request).build();
+
+		assertThat(observationContext.getRequest()).isEqualTo(request);
+		assertThat(observationContext.getRequest()).isSameAs(request);
+	}
+
+	@Test
+	void whenBuilderReusedThenReturnDifferentInstances() {
+		var builder = ChatClientObservationContext.builder()
+			.request(ChatClientRequest.builder().prompt(new Prompt()).build());
+
+		var context1 = builder.build();
+		var context2 = builder.build();
+
+		assertThat(context1).isNotSameAs(context2);
+	}
+
+	@Test
+	void whenNoAdvisorsSpecifiedThenGetAdvisorsReturnsEmptyOrNull() {
+		var observationContext = ChatClientObservationContext.builder()
+			.request(ChatClientRequest.builder().prompt(new Prompt()).build())
+			.build();
+
+		// Should return either empty list or null when no advisors specified
+		assertThat(observationContext.getAdvisors()).satisfiesAnyOf(advisors -> assertThat(advisors).isNull(),
+				advisors -> assertThat(advisors).isEmpty());
+	}
+
 }