test-javalin-jsonb: Added async request handling tests.

Author: Haydon Perrin

tests/test-javalin-jsonb/src/main/java/org/example/myapp/web/HelloController.java

@@ -5,6 +5,8 @@
 import java.time.LocalDate;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.Executors;
 
 import javax.validation.Valid;
 
@@ -142,6 +144,21 @@ List<HelloDto> getAll() {
     return myService.findAll();
   }
 
+  @Get("/async")
+  CompletableFuture<List<HelloDto>> getAllAsync() {
+    return CompletableFuture.supplyAsync(() -> {
+      // Simulate a delay as if an actual IO operation is being executed.
+      // This also helps ensure that we aren't just getting lucky with timings.
+      try {
+        Thread.sleep(10L);
+      } catch (InterruptedException e) {
+        throw new RuntimeException(e);
+      }
+
+      return myService.findAll();
+    }, Executors.newSingleThreadExecutor()); // Example of how to use a custom executor.
+  }
+
   //  @Hidden
   @Delete(":id")
   void deleteById(int id) {

tests/test-javalin-jsonb/src/test/java/org/example/myapp/HelloControllerTest.java

@@ -62,6 +62,25 @@ void hello2() {
     assertThat(helloDtos).hasSize(2);
   }
 
+  @Test
+  void helloAsyncRequestHandling() {
+    TypeRef<List<HelloDto>> listDto = new TypeRef<List<HelloDto>>() { };
+    final List<HelloDto> beans = given()
+      .get(baseUrl + "/hello/async")
+      .then()
+      .statusCode(200)
+      .extract()
+      .as(listDto);
+
+    assertThat(beans).hasSize(2);
+
+    final List<HelloDto> helloDtos = client.request()
+                                           .path("hello/async")
+                                           .GET().list(HelloDto.class);
+
+    assertThat(helloDtos).hasSize(2);
+  }
+
   @Test
   void getWithPathParamAndQueryParam() {