template: Make validation errors from failed pattern matches shorter

The pattern that was failed to match has been moved from "message" to
"details". The regex pattern can get very long, so to keep messages
short, it will now always be in "details".

Author: mstokes-f5

lib/template.js

@@ -1084,6 +1084,7 @@ class Template {
             const param = error.dataPath
                 .replace('.', ''); // strip leading dot
             let message = (param !== '') ? `parameter ${param} ${error.message}` : error.message;
+            let details = null;
 
             if (error.keyword === 'type') {
                 const typeStr = error.params.type;
@@ -1095,9 +1096,17 @@ class Template {
                 message = `${message}: ${allowedValues.join(', ')}`;
             }
 
-            return {
-                message
-            };
+            if (error.keyword === 'pattern') {
+                message = `parameter ${param} should match pattern`;
+                details = `failed to match pattern: ${error.params.pattern}`;
+            }
+
+            const newError = { message };
+            if (details) {
+                newError.details = details;
+            }
+
+            return newError;
         });
     }
 

test/template.js

@@ -1436,4 +1436,27 @@ describe('Template class tests', function () {
                 });
             });
     });
+    it('validate_pattern', function () {
+        const yamldata = `
+            definitions:
+                foo:
+                    pattern: bar
+            parameters:
+                foo: foo
+            template: |-
+                {{foo}}
+        `;
+
+        return Template.loadYaml(yamldata)
+            .then((tmpl) => {
+                assert.throws(() => tmpl.validateParameters(), {
+                    validationErrors: [
+                        {
+                            message: 'parameter foo should match pattern',
+                            details: 'failed to match pattern: bar'
+                        }
+                    ]
+                });
+            });
+    });
 });