feat: avoid redundant keyword repetition for array constraints (#171)

src/__tests__/index.ts

@@ -321,5 +321,45 @@ describe('Main', () => {
         },
       ]);
     });
+    it('formats array keyword errors (minItems, maxItems, uniqueItems) without awkward keyword repetition (#171)', () => {
+      const schema = {
+        type: 'object',
+        properties: {
+          operators: {
+            type: 'array',
+            minItems: 1,
+            maxItems: 3,
+            uniqueItems: true,
+          },
+        },
+      };
+
+      expect(getErrors(schema, { operators: [] })).toEqual([
+        {
+          start: { line: 1, column: 14, offset: 13 },
+          end: { line: 1, column: 16, offset: 15 },
+          error: '/operators: must NOT have fewer than 1 items',
+          path: '/operators',
+        },
+      ]);
+
+      expect(getErrors(schema, { operators: [1, 2, 3, 4] })).toEqual([
+        {
+          start: { line: 1, column: 14, offset: 13 },
+          end: { line: 1, column: 23, offset: 22 },
+          error: '/operators: must NOT have more than 3 items',
+          path: '/operators',
+        },
+      ]);
+
+      expect(getErrors(schema, { operators: [1, 1] })).toEqual([
+        {
+          start: { line: 1, column: 14, offset: 13 },
+          end: { line: 1, column: 19, offset: 18 },
+          error: '/operators: must NOT have duplicate items (items ## 0 and 1 are identical)',
+          path: '/operators',
+        },
+      ]);
+    });
   });
 });

src/validation-errors/default.ts

@@ -2,24 +2,29 @@ import { styleText } from 'node:util';
 import type { IOutputError } from '../index';
 import BaseValidationError from './base';
 
+const ARRAY_KEYWORDS = new Set(['minItems', 'maxItems', 'uniqueItems']);
+
 export default class DefaultValidationError extends BaseValidationError {
   print(): string[] {
     const { keyword, message } = this.options;
     const output = [
       styleText('red', styleText('bold', keyword.toUpperCase()) + ' ' + message) + '\n',
     ];
 
-    return output.concat(
-      this.getCodeFrame('👈🏽  ' + styleText('magentaBright', keyword) + ' ' + message)
-    );
+    const label = ARRAY_KEYWORDS.has(keyword)
+      ? message
+      : `${styleText('magentaBright', keyword)} ${message}`;
+
+    return output.concat(this.getCodeFrame(`👈🏽  ${label}`));
   }
 
   getError(): IOutputError {
     const { keyword, message } = this.options;
+    const errorMsg = ARRAY_KEYWORDS.has(keyword) ? (message ?? '') : `${keyword} ${message}`;
 
     return {
       ...this.getLocation(),
-      error: this.withDecoratedPath(`${keyword} ${message}`, ': '),
+      error: this.withDecoratedPath(errorMsg, ': '),
       path: this.instancePath,
     };
   }