Build a decent top level text message for ConstraintViolationException

blackbox-test/src/main/java/example/avaje/cascade/ACrew.java

@@ -4,5 +4,5 @@
 import io.avaje.validation.constraints.Valid;
 
 @Valid
-public record ACrew (@NotBlank(max = 4) String name, String role) {
+public record ACrew (@NotBlank(max = 4) String name) {
 }

blackbox-test/src/main/java/example/avaje/cascade/DShip.java

@@ -7,6 +7,7 @@
 @Valid
 public record DShip(
   @NotBlank String name,
+  @NotBlank String rating,
   @NotEmpty String[] crew // cascade validation
 ) {
 }

blackbox-test/src/test/java/example/avaje/ExceptionMessageTest.java

@@ -0,0 +1,116 @@
+package example.avaje;
+
+import example.avaje.cascade.ACrew;
+import example.avaje.cascade.BShip;
+import example.avaje.cascade.DShip;
+import io.avaje.validation.ConstraintViolationException;
+import io.avaje.validation.Validator;
+import org.junit.jupiter.api.Test;
+
+import java.util.LinkedHashSet;
+import java.util.Locale;
+import java.util.Set;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.fail;
+
+class ExceptionMessageTest {
+
+  Validator validator = Validator.builder().addLocales(Locale.GERMAN).build();
+
+  @Test
+  void oneError() {
+    var ship = new DShip("", "ok", new String[]{"ok"});
+    try {
+      validator.validate(ship);
+      fail("don't get here");
+    } catch (ConstraintViolationException e) {
+      assertThat(e.violations()).hasSize(1);
+      assertThat(e).hasMessage("1 constraint violation(s) occurred.\n" +
+        " name: must not be blank");
+    }
+  }
+
+  @Test
+  void twoErrors() {
+    var ship = new DShip("", "", new String[]{"ok"});
+    try {
+      validator.validate(ship);
+      fail("don't get here");
+    } catch (ConstraintViolationException e) {
+      assertThat(e.violations()).hasSize(2);
+      assertThat(e).hasMessage("2 constraint violation(s) occurred.\n" +
+        " name: must not be blank\n" +
+        " rating: must not be blank");
+    }
+  }
+
+  @Test
+  void threeErrors() {
+    var ship = new DShip("", "", null);
+    try {
+      validator.validate(ship);
+      fail("don't get here");
+    } catch (ConstraintViolationException e) {
+      assertThat(e.violations()).hasSize(3);
+      assertThat(e).hasMessage("3 constraint violation(s) occurred.\n" +
+        " name: must not be blank\n" +
+        " rating: must not be blank\n" +
+        " crew: must not be empty");
+    }
+  }
+
+  @Test
+  void tenErrors() {
+    var ship = new BShip("", createBadCrew(9));
+    try {
+      validator.validate(ship);
+      fail("don't get here");
+    } catch (ConstraintViolationException e) {
+      assertThat(e.violations()).hasSize(10);
+      assertThat(e).hasMessage("10 constraint violation(s) occurred.\n" +
+        " name: must not be blank\n" +
+        " crew[0].name: maximum length 4 exceeded\n" +
+        " crew[1].name: maximum length 4 exceeded\n" +
+        " crew[2].name: maximum length 4 exceeded\n" +
+        " crew[3].name: maximum length 4 exceeded\n" +
+        " crew[4].name: maximum length 4 exceeded\n" +
+        " crew[5].name: maximum length 4 exceeded\n" +
+        " crew[6].name: maximum length 4 exceeded\n" +
+        " crew[7].name: maximum length 4 exceeded\n" +
+        " crew[8].name: maximum length 4 exceeded");
+    }
+  }
+
+  @Test
+  void elevenErrors() {
+    var ship = new BShip("", createBadCrew(10));
+    try {
+      validator.validate(ship);
+      fail("don't get here");
+    } catch (ConstraintViolationException e) {
+      assertThat(e.violations()).hasSize(11);
+      assertThat(e).hasMessage("11 constraint violation(s) occurred.\n" +
+        " name: must not be blank\n" +
+        " crew[0].name: maximum length 4 exceeded\n" +
+        " crew[1].name: maximum length 4 exceeded\n" +
+        " crew[2].name: maximum length 4 exceeded\n" +
+        " crew[3].name: maximum length 4 exceeded\n" +
+        " crew[4].name: maximum length 4 exceeded\n" +
+        " crew[5].name: maximum length 4 exceeded\n" +
+        " crew[6].name: maximum length 4 exceeded\n" +
+        " crew[7].name: maximum length 4 exceeded\n" +
+        " crew[8].name: maximum length 4 exceeded\n" +
+        " and 1 other error(s)");
+    }
+  }
+
+  private Set<ACrew> createBadCrew(int count) {
+    Set<ACrew> set = new LinkedHashSet<>();
+    for (int i = 0; i < count; i++) {
+      set.add(new ACrew("abcd" + i));
+    }
+    return set;
+  }
+
+}

blackbox-test/src/test/java/example/avaje/cascade/AShipTest.java

@@ -19,31 +19,31 @@ class AShipTest {
 
   @Test
   void valid() {
-    var ship = new AShip("lollyPop", List.of(new ACrew("ok", null)));
+    var ship = new AShip("lollyPop", List.of(new ACrew("ok")));
     validator.validate(ship);
   }
 
   @Test
   void valid_usingSet() {
-    var ship = new BShip("lollyPop", Set.of(new ACrew("ok", null)));
+    var ship = new BShip("lollyPop", Set.of(new ACrew("ok")));
     validator.validate(ship);
   }
 
   @Test
   void valid_usingArray() {
-    var ship = new CShip("lollyPop", new ACrew[]{new ACrew("ok", null)});
+    var ship = new CShip("lollyPop", new ACrew[]{new ACrew("ok")});
     validator.validate(ship);
   }
 
   @Test
   void valid_usingArray3() {
-    var ship = new CShip3("lollyPop", new ACrew[]{new ACrew("ok", null)});
+    var ship = new CShip3("lollyPop", new ACrew[]{new ACrew("ok")});
     validator.validate(ship);
   }
 
   @Test
   void valid_usingScalarArray() {
-    var ship = new DShip("lollyPop", new String[]{"bob"});
+    var ship = new DShip("lollyPop", "ok", new String[]{"bob"});
     validator.validate(ship);
   }
 
@@ -61,19 +61,19 @@ void validAllowNullCollection() {
 
   @Test
   void valid2() {
-    var ship = new AShip2("lollyPop", List.of(new ACrew("ok", null)));
+    var ship = new AShip2("lollyPop", List.of(new ACrew("ok")));
     validator.validate(ship);
   }
 
   @Test
   void valid3_expect_noCascadeValidationToCrew() {
-    var ship = new AShip3("lollyPop", List.of(new ACrew("NotValid", null)));
+    var ship = new AShip3("lollyPop", List.of(new ACrew("NotValid")));
     validator.validate(ship);
   }
 
   @Test
   void invalid() {
-    var ship = new AShip("", List.of(new ACrew("NotValid", null)));
+    var ship = new AShip("", List.of(new ACrew("NotValid")));
     List<ConstraintViolation> violations = violations(ship);
 
     assertThat(violations).hasSize(2);
@@ -109,7 +109,7 @@ void invalidShip2_when_nullCollection_expect_InvalidEmptyCollection() {
 
   @Test
   void arrayCascade() {
-    var ship = new CShip("", new ACrew[]{new ACrew("NotValid", null)});
+    var ship = new CShip("", new ACrew[]{new ACrew("NotValid")});
     List<ConstraintViolation> violations = violations(ship);
 
     assertThat(violations).hasSize(2);
@@ -121,7 +121,7 @@ void arrayCascade() {
 
   @Test
   void arrayNotCascade() {
-    var ship = new CShip3("", new ACrew[]{new ACrew("NotValid", null)});
+    var ship = new CShip3("", new ACrew[]{new ACrew("NotValid")});
     List<ConstraintViolation> violations = violations(ship);
 
     assertThat(violations).hasSize(1);
@@ -153,7 +153,7 @@ void arrayNotEmpty_when_null() {
 
   @Test
   void arrayNotEmpty_when_scalarArrayEmpty() {
-    var ship = new DShip("", new String[]{});
+    var ship = new DShip("", "ok", new String[]{});
     List<ConstraintViolation> violations = violations(ship);
 
     assertThat(violations).hasSize(2);
@@ -165,7 +165,7 @@ void arrayNotEmpty_when_scalarArrayEmpty() {
 
   @Test
   void arrayNotEmpty_when_scalarNull() {
-    var ship = new DShip("ok", null);
+    var ship = new DShip("ok", "ok", null);
     List<ConstraintViolation> violations = violations(ship);
 
     assertThat(violations).hasSize(1);

validator/src/main/java/io/avaje/validation/ConstraintViolationException.java

@@ -1,17 +1,20 @@
 package io.avaje.validation;
 
+import java.io.Serial;
 import java.util.List;
 import java.util.Set;
 
 /** Exception holding a set of constraint violations. */
 public final class ConstraintViolationException extends RuntimeException {
 
+  @Serial
   private static final long serialVersionUID = 1L;
   private final transient Set<ConstraintViolation> violations;
   private final transient List<Class<?>> groups;
 
   /** Create with the given constraint violations */
-  public ConstraintViolationException(Set<ConstraintViolation> violations, List<Class<?>> groups) {
+  public ConstraintViolationException(String message, Set<ConstraintViolation> violations, List<Class<?>> groups) {
+    super(message);
     this.violations = violations;
     this.groups = groups;
   }

validator/src/main/java/io/avaje/validation/core/DRequest.java

@@ -76,10 +76,23 @@ public void popPath() {
   @Override
   public void throwWithViolations() {
     if (!violations.isEmpty()) {
-      throw new ConstraintViolationException(violations, groups);
+      throw new ConstraintViolationException(message(), violations, groups);
     }
   }
 
+  private String message() {
+    final var msg = new StringBuilder(100);
+    msg.append(violations.size()).append(" constraint violation(s) occurred.");
+    violations.stream().limit(10).forEach(cv -> {
+      msg.append("\n ").append(cv.path()).append(": ").append(cv.message());
+    });
+    final int others = violations.size() - 10;
+    if (others > 0) {
+      msg.append("\n and ").append(others).append(" other error(s)");
+    }
+    return msg.toString();
+  }
+
   @Override
   public Set<ConstraintViolation> violations() {
     return violations;