Explicit flush example with JPA EntityManager

Issue: SPR-13723

src/asciidoc/testing.adoc

@@ -3278,14 +3278,13 @@ declarative SQL script execution with default transaction rollback semantics.
 .Avoid false positives when testing ORM code
 [NOTE]
 ====
-When you test application code that manipulates the state of the Hibernate session, make
-sure to __flush__ the underlying session within test methods that execute that code.
+When you test application code that manipulates the state of the Hibernate or JPA session,
+make sure to __flush__ the underlying session within test methods that execute that code.
 Failing to flush the underlying session can produce __false positives__: your test may
 pass, but the same code throws an exception in a live, production environment. In the
 following Hibernate-based example test case, one method demonstrates a false positive,
 and the other method correctly exposes the results of flushing the session. Note that
-this applies to JPA and any other ORM frameworks that maintain an in-memory __unit of
-work__.
+this applies to any ORM frameworks that maintain an in-memory __unit of work__.
 
 [source,java,indent=0]
 [subs="verbatim,quotes"]
@@ -3298,11 +3297,11 @@ work__.
 	@Test // no expected exception!
 	public void falsePositive() {
 		updateEntityInHibernateSession();
-		// False positive: an exception will be thrown once the session is
-		// finally flushed (i.e., in production code)
+		// False positive: an exception will be thrown once the Hibernate
+		// Session is finally flushed (i.e., in production code)
 	}
 
-	@Test(expected = GenericJDBCException.class)
+	@Test(expected = ...)
 	public void updateWithSessionFlush() {
 		updateEntityInHibernateSession();
 		// Manual flush is required to avoid false positive in test
@@ -3311,6 +3310,33 @@ work__.
 
 	// ...
 ----
+
+Or for JPA:
+
+[source,java,indent=0]
+[subs="verbatim,quotes"]
+----
+	// ...
+
+	@Autowired
+	private EntityManager entityManager;
+
+	@Test // no expected exception!
+	public void falsePositive() {
+		updateEntityInJpaTransaction();
+		// False positive: an exception will be thrown once the JPA
+		// EntityManager is finally flushed (i.e., in production code)
+	}
+
+	@Test(expected = ...)
+	public void updateWithEntityManagerFlush() {
+		updateEntityInJpaTransaction();
+		// Manual flush is required to avoid false positive in test
+		entityManager.flush();
+	}
+
+	// ...
+----
 ====