Merge pull request #1657 from jwatkinsdavid-scottlogic/fix/1553-if-co…

…nstraint-error-message

fix(#1553): Improve error message from invalid conditional constraint

profile/src/main/java/com/scottlogic/datahelix/generator/profile/validators/profile/constraints/grammatical/ConditionalConstraintValidator.java

@@ -33,7 +33,9 @@ public ConditionalConstraintValidator(List<FieldDTO> fields)
     public ValidationResult validate(ConditionalConstraintDTO conditionalConstraint)
     {
         ValidationResult validateIfConstraint = validateConstraint(conditionalConstraint.ifConstraint, fields);
-        ValidationResult validateThenConstraint = validateConstraint(conditionalConstraint.thenConstraint, fields);
+        ValidationResult validateThenConstraint = conditionalConstraint.thenConstraint == null
+            ? ValidationResult.failure("'if' constraint must also have an associated 'then' constraint")
+            : validateConstraint(conditionalConstraint.thenConstraint, fields);
         ValidationResult validateElseConstraint = conditionalConstraint.elseConstraint == null
             ? ValidationResult.success()
             :validateConstraint(conditionalConstraint.ifConstraint, fields);

profile/src/test/java/com/scottlogic/datahelix/generator/profile/validators/profile/constraints/grammatical/ConditionalConstraintValidatorTests.java

@@ -0,0 +1,61 @@
+/*
+ * Copyright 2020 Scott Logic Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.scottlogic.datahelix.generator.profile.validators.profile.constraints.grammatical;
+
+import com.scottlogic.datahelix.generator.common.profile.StandardSpecificFieldType;
+import com.scottlogic.datahelix.generator.common.validators.ValidationResult;
+import com.scottlogic.datahelix.generator.profile.creation.FieldDTOBuilder;
+import com.scottlogic.datahelix.generator.profile.dtos.FieldDTO;
+import com.scottlogic.datahelix.generator.profile.dtos.constraints.atomic.EqualToConstraintDTO;
+import com.scottlogic.datahelix.generator.profile.dtos.constraints.grammatical.ConditionalConstraintDTO;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class ConditionalConstraintValidatorTests {
+
+    private final List<FieldDTO> fields = Arrays.asList
+        (
+            FieldDTOBuilder.create("integer", StandardSpecificFieldType.INTEGER.toSpecificFieldType())
+        );
+
+    @Test
+    public void validateConditionalConstraint_withNullThenConstraint_shouldResultInValidationFailure()
+    {
+        // Arrange
+        EqualToConstraintDTO equalToConstraint = new EqualToConstraintDTO();
+        equalToConstraint.field = "integer";
+        equalToConstraint.value = 1;
+
+        ConditionalConstraintDTO dto = new ConditionalConstraintDTO();
+        dto.ifConstraint = equalToConstraint;
+        dto.thenConstraint = null;
+        dto.elseConstraint  = null;
+
+        // Act
+        ValidationResult validationResult = new ConditionalConstraintValidator(fields).validate(dto);
+
+        // Assert
+        assertFalse(validationResult.isSuccess);
+        assertEquals(1, validationResult.errors.size());
+        assertTrue(validationResult.errors.contains("'if' constraint must also have an associated 'then' constraint"));
+    }
+}