diff --git a/src/test/java/com/ankurm/sdjpa4demo/MigrationBehaviorTests.java b/src/test/java/com/ankurm/sdjpa4demo/MigrationBehaviorTests.java
new file mode 100644
index 0000000..a3c078f
--- /dev/null
+++ b/src/test/java/com/ankurm/sdjpa4demo/MigrationBehaviorTests.java
@@ -0,0 +1,81 @@
+package com.ankurm.sdjpa4demo;
+
+import com.ankurm.sdjpa4demo.domain.Author;
+import com.ankurm.sdjpa4demo.domain.Book;
+import com.ankurm.sdjpa4demo.repo.AuthorRepository;
+import com.ankurm.sdjpa4demo.repo.BookRepository;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.dao.EmptyResultDataAccessException;
+import org.springframework.dao.IncorrectResultSizeDataAccessException;
+import org.springframework.data.domain.Sort;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.math.BigDecimal;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+@SpringBootTest
+@ActiveProfiles("test")
+@Transactional
+class MigrationBehaviorTests {
+
+    @Autowired AuthorRepository authors;
+    @Autowired BookRepository books;
+
+    private void seed() {
+        Author a1 = authors.save(new Author("Joshua Bloch", "US"));
+        authors.save(new Author("Anonymous", null));
+        books.save(new Book("Effective Java", new BigDecimal("45.00"), a1));
+        books.save(new Book("Refactoring", new BigDecimal("45.00"), a1));
+    }
+
+    @Test
+    void optionalMissingReturnsEmpty() {
+        seed();
+        assertTrue(authors.findByName("nope").isEmpty());
+    }
+
+    @Test
+    void nonNullMissingThrows() {
+        seed();
+        assertThrows(EmptyResultDataAccessException.class, () -> authors.getByName("nope"));
+    }
+
+    @Test
+    void nullMarkedRejectsNullArgument() {
+        seed();
+        assertThrows(IllegalArgumentException.class, () -> authors.getByName(null));
+    }
+
+    @Test
+    void nullableParamAcceptsNull() {
+        seed();
+        assertDoesNotThrow(() -> authors.findByCountry(null));
+    }
+
+    @Test
+    void nullsPrecedenceIsHonored() {
+        seed();
+        List<String> first = authors.findByNameStartingWith("",
+                Sort.by(Sort.Order.asc("country").nullsFirst()))
+                .stream().map(Author::getCountry).toList();
+        assertNull(first.get(0), "NULLS FIRST should put null country first");
+    }
+
+    @Test
+    void nonUniqueSingleResultThrows() {
+        seed();
+        assertThrows(IncorrectResultSizeDataAccessException.class,
+                () -> books.findByPrice(new BigDecimal("45.00")));
+    }
+
+    @Test
+    void newJpqlFunctionsWork() {
+        Author a = authors.save(new Author("Erich Gamma", "CH"));
+        assertEquals("Erich_Gamma:CH", authors.badgeFor(a.getId()));
+    }
+}