feat: add pattern and path to regexp create errors #2477

lib/vocabularies/code.ts

@@ -1,4 +1,4 @@
-import type {AnySchema, SchemaMap} from "../types"
+import type {AnySchema, RegExpLike, SchemaMap} from "../types"
 import type {SchemaCxt} from "../compile"
 import type {KeywordCxt} from "../compile/validate"
 import {CodeGen, _, and, or, not, nil, strConcat, getProperty, Code, Name} from "../compile/codegen"
@@ -92,10 +92,16 @@ export function callValidateCode(
 
 const newRegExp = _`new RegExp`
 
-export function usePattern({gen, it: {opts}}: KeywordCxt, pattern: string): Name {
+export function usePattern({gen, it: {opts, errSchemaPath}}: KeywordCxt, pattern: string): Name {
   const u = opts.unicodeRegExp ? "u" : ""
   const {regExp} = opts.code
-  const rx = regExp(pattern, u)
+
+  let rx: RegExpLike
+  try {
+    rx = regExp(pattern, u)
+  } catch (e) {
+    throw new Error(`${(e as Error).message} | pattern ${pattern} at ${errSchemaPath}`)
+  }
 
   return gen.scopeValue("pattern", {
     key: rx.toString(),

lib/vocabularies/validation/pattern.ts

@@ -18,9 +18,16 @@ const def: CodeKeywordDefinition = {
   error,
   code(cxt: KeywordCxt) {
     const {data, $data, schema, schemaCode, it} = cxt
-    // TODO regexp should be wrapped in try/catchs
     const u = it.opts.unicodeRegExp ? "u" : ""
-    const regExp = $data ? _`(new RegExp(${schemaCode}, ${u}))` : usePattern(cxt, schema)
+    const regExp = $data
+      ? _`(function() {
+        try {
+          return new RegExp(${schemaCode}, ${u})
+        } catch (e) {
+          throw new Error(e.message + ' | pattern ' + ${schemaCode} + ' at ' + ${it.errSchemaPath})
+        }
+      })()`
+      : usePattern(cxt, schema)
     cxt.fail$data(_`!${regExp}.test(${data})`)
   },
 }

spec/issues/2477_informative_pattern_errors.spec.ts

@@ -0,0 +1,46 @@
+import _Ajv from "../ajv2020"
+import * as assert from "assert"
+
+describe("Invalid regexp patterns should throw more informative errors (issue #2477)", () => {
+  it("throws with pattern and schema path", () => {
+    const ajv = new _Ajv()
+
+    const rootSchema = {
+      type: "string",
+      pattern: "^[0-9]{2-4}",
+    }
+
+    assert.throws(
+      () => ajv.compile(rootSchema),
+      (thrown: Error) => thrown.message.includes("pattern ^[0-9]{2-4} at #")
+    )
+
+    const pathSchema = {
+      type: "object",
+      properties: {
+        foo: rootSchema,
+      },
+    }
+
+    assert.throws(
+      () => ajv.compile(pathSchema),
+      (thrown: Error) => thrown.message.includes("pattern ^[0-9]{2-4} at #/properties/foo")
+    )
+  })
+  it("throws with pattern and schema path with $data", () => {
+    const ajv = new _Ajv({$data: true})
+
+    const schema = {
+      properties: {
+        shouldMatch: {},
+        string: {pattern: {$data: "1/shouldMatch"}},
+      },
+    }
+    const validate = ajv.compile(schema)
+
+    assert.throws(
+      () => ajv.compile(validate({shouldMatch: "^[0-9]{2-4}", string: "123"})),
+      (thrown: Error) => thrown.message.includes("pattern ^[0-9]{2-4} at #/properties/string")
+    )
+  })
+})