std/regexp/escape_test.ts

// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.

import { escape } from "./escape.ts";
import { assertEquals, assertMatch, assertNotMatch } from "@std/assert";

const ALL_ASCII =
  "\x00\x01\x02\x03\x04\x05\x06\x07\b\t\n\v\f\r\x0E\x0F\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1A\x1B\x1C\x1D\x1E\x1F !\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~\x7F";
const ALL_REGEXP_FLAGS = "gimsuy";

Deno.test("escape() works with examples", async (t) => {
  await t.step("`.` matches literal `.`", () => {
    const re = new RegExp(`^${escape(".")}$`, "u");

    assertEquals("^\\.$", re.source);
    assertMatch(".", re);
    assertNotMatch("a", re);
  });
  await t.step("`$` matches literal `$`", () => {
    const re = new RegExp(`^${escape("$")}$`);

    assertMatch("$", re);
    assertNotMatch("", re);
  });
  await t.step("`*` matches literal `*`", () => {
    const re = new RegExp(`^${escape("a*")}$`);

    assertMatch("a*", re);
    assertNotMatch("", re);
    assertNotMatch("aaa", re);
  });
  await t.step("escapes works correctly within character class", () => {
    const re = new RegExp(`^[${escape(".$*+[](){}|\\<>")}]$`);

    assertMatch(".", re);
    assertMatch("$", re);
    assertMatch("*", re);
    assertMatch("+", re);
    assertMatch("[", re);
    assertMatch("]", re);
    assertMatch("(", re);
    assertMatch(")", re);
    assertMatch("{", re);
    assertMatch("}", re);
    assertMatch("|", re);
    assertMatch("\\", re);
    assertMatch("<", re);
    assertMatch(">", re);

    assertNotMatch("a", re);
  });
});
Deno.test("escape() works with all ASCII", async (t) => {
  await t.step("interpolates without erroring", async (t) => {
    await t.step("outside character class", () => {
      for (const char of ALL_ASCII) {
        for (const flag of ALL_REGEXP_FLAGS) {
          new RegExp(escape(char), flag);
        }
      }
    });
    await t.step("within character class", () => {
      for (const char of ALL_ASCII) {
        for (const flag of ALL_REGEXP_FLAGS) {
          new RegExp(`[${escape(char)}]`, flag);
        }
      }
    });
    await t.step("matches self", () => {
      for (const char of ALL_ASCII) {
        for (const flag of ALL_REGEXP_FLAGS) {
          assertMatch(char, new RegExp(`^${escape(char)}$`, flag));
        }
      }
    });
    await t.step("doesn't match any other chars", () => {
      for (const char of ALL_ASCII) {
        for (const flag of ALL_REGEXP_FLAGS) {
          if (flag === "i") continue;

          for (const char2 of ALL_ASCII) {
            if (char2 === char) continue;

            assertNotMatch(
              char2,
              new RegExp(`^${escape(char)}$`, flag),
            );
          }
        }
      }
    });
  });
});