test: parse/stringify roundtrip preserves equivalence

Author: gruhn

test/index.spec.ts

@@ -86,7 +86,7 @@ describe('isEquivalent', () => {
 
 describe('without', () => {
   const withoutCases = [
-    [/^a*$/, /^a{3,10}$/, /^(a{,2}|a{11,})$/],
+    [/^a*$/, /^a{3,10}$/, /^(a{0,2}|a{11,})$/],
   ]
   for (const [re1, re2, expected] of withoutCases) {
     test(`${re1} without ${re2} is ${expected}`, () => {

test/regex-parser.spec.ts

@@ -1,9 +1,12 @@
-import { describe, it } from "node:test"
+import { describe, it, test } from "node:test"
 import assert from "node:assert"
 import { parseRegExp, parseRegExpString } from "../src/regex-parser"
+import { RB } from "../src/index"
 import { ParseError } from "../src/parser"
 import * as AST from "../src/ast"
 import * as CharSet from "../src/char-set"
+import fc from "fast-check"
+import * as Arbitrary from './arbitrary-ast'
 
 // Helper functions for cleaner test construction
 function char(c: string) {
@@ -130,3 +133,25 @@ describe('parseRegExp', () => {
   })
 
 })
+
+test('parse/stringify roundtrip preserves equivalence', { todo: true }, () => {
+  fc.assert(
+    fc.property(
+      Arbitrary.regexp(),
+      (inputRegExp) => {
+        const builder = RB(inputRegExp)
+        const outputRegExp = builder.toRegExp()
+
+        // console.debug(inputRegExp)
+        // console.debug(outputRegExp)
+
+        for (const str of builder.enumerate().take(10)) {
+          assert.match(str, outputRegExp)
+          assert.match(str, inputRegExp)
+        }
+      }
+    ),
+    { seed: -1651123632, path: "89:0", endOnFailure: true }
+  )
+})
+

test/regex.spec.ts

@@ -311,6 +311,13 @@ describe('fromRegExpAST', () => {
         assert.equal(actual.hash, expected.hash, RE.debugShow(actual) + '\n\n' + RE.debugShow(expected))
       })
     }
+
+    it('fixme', { todo: true }, () => {
+      const actual = RE.fromRegExpAST(parseRegExp(/^(a(?!b))*$/))
+      const expected = RE.star(RE.string('a'))
+      assert.equal(actual.hash, expected.hash) 
+    })
+
   })
 
 })