BAEL-7783: Assert properties of custom exceptions with catchThrowableOfType in AssertJ (#16442)

testing-modules/assertion-libraries/src/main/java/com/baeldung/assertj/exceptions/CityNotFoundException.java

@@ -0,0 +1,22 @@
+package com.baeldung.assertj.exceptions;
+
+public class CityNotFoundException extends RuntimeException {
+
+    private String city;
+    private String message;
+
+    CityNotFoundException(String city, String message) {
+        this.city = city;
+        this.message = message;
+    }
+
+    public String getCity() {
+        return city;
+    }
+
+    @Override
+    public String getMessage() {
+        return message;
+    }
+
+}

testing-modules/assertion-libraries/src/main/java/com/baeldung/assertj/exceptions/CityUtils.java

@@ -0,0 +1,17 @@
+package com.baeldung.assertj.exceptions;
+
+import java.util.Arrays;
+import java.util.List;
+
+public final class CityUtils {
+
+    private static final List<String> CITIES = Arrays.asList("Tamassint", "London", "Madrid", "New york");
+
+    public static String search(String searchedCity) {
+        return CITIES.stream()
+            .filter(searchedCity::equals)
+            .findFirst()
+            .orElseThrow(() -> new CityNotFoundException(searchedCity, "The specified city is not found"));
+    }
+
+}

testing-modules/assertion-libraries/src/test/java/com/baeldung/assertj/exceptions/Java8StyleAssertions.java

@@ -1,13 +1,15 @@
 package com.baeldung.assertj.exceptions;
 
-import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 import static org.assertj.core.api.Assertions.catchThrowable;
+import static org.assertj.core.api.Assertions.catchThrowableOfType;
 
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Arrays;
+
 import org.junit.Test;
 
 public class Java8StyleAssertions {
@@ -63,4 +65,22 @@ public class Java8StyleAssertions {
             .hasMessageContaining("/ by zero");
 
     }
+
+    @Test
+    public void whenUsingCatchThrowableOfType_thenAssertField() {
+        String givenCity = "Paris";
+        CityNotFoundException exception = catchThrowableOfType(() -> CityUtils.search(givenCity), CityNotFoundException.class);
+
+        assertThat(exception.getCity()).isEqualTo(givenCity);
+        assertThat(exception.getMessage()).isEqualTo("The specified city is not found");
+    }
+
+    @Test
+    public void whenUsingAssertThatThrownBy_thenAssertField() {
+        String givenCity = "Geneva";
+        assertThatThrownBy(() -> CityUtils.search(givenCity)).isInstanceOf(CityNotFoundException.class)
+          .extracting("city")
+          .isEqualTo(givenCity);
+    }
+
 }