test: add SwaggerResponseCustomizer unit test, extend CustomerControllerIT with extra scenarios, and add CustomerServiceApplicationIT for context load

Author: barissayli

customer-service/src/test/java/io/github/bsayli/customerservice/CustomerServiceApplicationIT.java

@@ -0,0 +1,18 @@
+package io.github.bsayli.customerservice;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.api.Test;
+import org.springframework.boot.test.context.SpringBootTest;
+
+@SpringBootTest
+@Tag("integration")
+@DisplayName("Integration Test: Application Context")
+class CustomerServiceApplicationIT {
+
+    @Test
+    @DisplayName("Spring context should load without issues")
+    void contextLoads() {
+        // If the context fails to start, this test will fail
+    }
+}

customer-service/src/test/java/io/github/bsayli/customerservice/api/controller/CustomerControllerIT.java

@@ -16,9 +16,11 @@
 import io.github.bsayli.customerservice.testconfig.TestControllerMocksConfig;
 import java.util.List;
 import java.util.NoSuchElementException;
+import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Tag;
 import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
 import org.springframework.context.annotation.Import;
@@ -161,4 +163,50 @@ void deleteCustomer_ok200() throws Exception {
         .andExpect(jsonPath("$.data.customerId").value(1))
         .andExpect(jsonPath("$.data.deletedAt").exists());
   }
+
+  @Test
+  @DisplayName("POST /v1/customers -> 400 Bad Request when JSON is malformed")
+  void createCustomer_badJson_notReadable() throws Exception {
+    var malformed = "{ \"name\": \"John\", \"email\": }"; // invalid JSON
+
+    mvc.perform(
+                    post("/v1/customers")
+                            .contentType(MediaType.APPLICATION_JSON)
+                            .content(malformed))
+            .andExpect(status().isBadRequest())
+            .andExpect(content().contentType(MediaType.APPLICATION_JSON))
+            .andExpect(jsonPath("$.message").value("BAD_REQUEST"))
+            .andExpect(jsonPath("$.data.code").value("VALIDATION_FAILED"))
+            .andExpect(jsonPath("$.data.violations").isArray());
+  }
+
+  @Test
+  @DisplayName("GET /v1/customers/{id} -> 400 Bad Request on @Min violation (id=0)")
+  void getCustomer_constraintViolation_min() throws Exception {
+    mvc.perform(get("/v1/customers/{id}", 0)) // @Min(1) violated
+            .andExpect(status().isBadRequest())
+            .andExpect(content().contentType(MediaType.APPLICATION_JSON))
+            .andExpect(jsonPath("$.message").value("BAD_REQUEST"))
+            .andExpect(jsonPath("$.data.code").value("VALIDATION_FAILED"))
+            .andExpect(jsonPath("$.data.violations").isArray())
+            .andExpect(jsonPath("$.data.violations[0].message").exists());
+  }
+
+  @Test
+  @DisplayName("GET /v1/customers/{id} -> 500 Internal Server Error handled by advice")
+  void getCustomer_internalServerError_generic() throws Exception {
+    when(customerService.getCustomer(1)).thenThrow(new RuntimeException("Boom"));
+
+    mvc.perform(get("/v1/customers/{id}", 1))
+            .andExpect(status().isInternalServerError())
+            .andExpect(content().contentType(MediaType.APPLICATION_JSON))
+            .andExpect(jsonPath("$.message").value("INTERNAL_ERROR"))
+            .andExpect(jsonPath("$.data.code").value("INTERNAL_ERROR"))
+            .andExpect(jsonPath("$.data.message").value("Boom"));
+  }
+
+  @AfterEach
+  void resetMocks() {
+    Mockito.reset(customerService);
+  }
 }

customer-service/src/test/java/io/github/bsayli/customerservice/common/openapi/SwaggerResponseCustomizerTest.java

@@ -0,0 +1,49 @@
+package io.github.bsayli.customerservice.common.openapi;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import io.swagger.v3.oas.models.Components;
+import io.swagger.v3.oas.models.OpenAPI;
+import io.swagger.v3.oas.models.media.Schema;
+import java.util.HashMap;
+import java.util.Map;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Tag;
+import org.junit.jupiter.api.Test;
+import org.springdoc.core.customizers.OpenApiCustomizer;
+
+@Tag("unit")
+@DisplayName("Unit Test: SwaggerResponseCustomizer")
+class SwaggerResponseCustomizerTest {
+
+  private final SwaggerResponseCustomizer config = new SwaggerResponseCustomizer();
+  private final OpenApiCustomizer customizer = config.responseEnvelopeSchemas();
+
+  @Test
+  @DisplayName("Should add missing schemas when absent")
+  void shouldAddSchemasWhenAbsent() {
+    OpenAPI openAPI = new OpenAPI().components(new Components().schemas(new HashMap<>()));
+
+    customizer.customise(openAPI);
+
+    @SuppressWarnings("rawtypes")
+    Map<String, Schema> schemas = openAPI.getComponents().getSchemas();
+    assertNotNull(schemas.get(OpenApiSchemas.SCHEMA_SERVICE_RESPONSE));
+    assertNotNull(schemas.get(OpenApiSchemas.SCHEMA_SERVICE_RESPONSE_VOID));
+  }
+
+  @Test
+  @DisplayName("Should not override existing schemas")
+  void shouldNotOverrideExistingSchemas() {
+    Schema<?> existing = new Schema<>().description("pre-existing");
+    Components components = new Components().schemas(new HashMap<>());
+    components.addSchemas(OpenApiSchemas.SCHEMA_SERVICE_RESPONSE, existing);
+    OpenAPI openAPI = new OpenAPI().components(components);
+
+    customizer.customise(openAPI);
+
+    Schema<?> result =
+            openAPI.getComponents().getSchemas().get(OpenApiSchemas.SCHEMA_SERVICE_RESPONSE);
+    assertSame(existing, result, "Existing schema should remain unchanged");
+  }
+}