fix(validation): shouldPublish should accept 'preserve' in addition to boolean values (#165)

## Summary

shouldPublish should accept 'preserve' in addition to boolean values

## Description

Add 'preserve' as a valid option to validations for shouldPublish field

## Motivation and Context

#143 (comment)

Author: jarkkosyrjala

src/lib/intent-validator/content-transform.ts

@@ -23,7 +23,7 @@ class ContentTransformIntentValidator extends SchemaValidator {
       from: Joi.array().items(Joi.string()).required(),
       to: Joi.array().items(Joi.string()).required(),
       transformEntryForLocale: Joi.func().required(),
-      shouldPublish: Joi.boolean()
+      shouldPublish: Joi.alternatives().try(Joi.boolean(), Joi.string().valid('preserve'))
     }
   }
 }

src/lib/intent-validator/schema-validator.ts

@@ -16,6 +16,13 @@ const validationErrors = {
   },
   INVALID_PROPERTY_TYPE: (propName, typeName, actualType, expectedType) => {
     return `"${actualType}" is not a valid type for the ${typeName} property "${propName}". Expected "${expectedType}".`
+  },
+  INVALID_VALUE_IN_ALTERNATIVES: (propName, typeName, value, schemaInnerMatches) => {
+    const expectedTypes = schemaInnerMatches.map( (match) => {
+      const validsSet = match.schema._valids._set
+      return validsSet.length > 0 ? `${match.schema._type} value ${validsSet.map(validValue => `"${validValue}"`).join(' or ')}` : `type ${match.schema._type}`
+    })
+    return `"${value}" is not a valid value for the ${typeName} property "${propName}". Expected ${expectedTypes.join(' or ')}.`
   }
 }
 
@@ -81,8 +88,10 @@ abstract class SchemaValidator implements IntentValidator {
             expectedType = 'function'
           }
           const actualType = kindOf(value)
-
-          const message = validationErrors.INVALID_PROPERTY_TYPE(propName, displayName, actualType, expectedType)
+          const message =
+              expectedType === 'alternatives' ?
+                validationErrors.INVALID_VALUE_IN_ALTERNATIVES(propName, displayName, error._object, schema._inner.matches)
+                : validationErrors.INVALID_PROPERTY_TYPE(propName, displayName, actualType, expectedType)
           errors.push({
             type: 'InvalidType',
             message,

test/unit/lib/intent-validator/content-transform.spec.ts

@@ -157,7 +157,7 @@ describe('Content transformation', function () {
                 type: 'contentType/transformEntries'
               }
             },
-            message: '"string" is not a valid type for the content transformation property "shouldPublish". Expected "boolean".',
+            message: '"yes please" is not a valid value for the content transformation property "shouldPublish". Expected type boolean or string value "preserve".',
             type: 'InvalidType'
           }
         ])