std/regexp/escape_test.ts

// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.

import { escape } from "./escape.ts";
import {
  assertEquals,
  assertMatch,
  assertNotMatch,
} from "../testing/asserts.ts";

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("regexp", async (t) => {
  await t.step("escape", async (t) => {
    await t.step("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 work 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);
      });
    });
    await t.step("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),
                );
              }
            }
          }
        });
      });
    });
  });
});