Differentially test linear-time regexp support for BusyBox

Create a unit test that differentially tests the change in BusyBox
escaping from "normal" regular expression to linear-time-based regular
expressions (in [1]). The (updates to the) `2410.patch` file accounts
for a later bug fix (see [2]).

[1]: e582b3e
[2]: 6add105

Author: John Doe

.github/workflows/checks.yml

@@ -364,7 +364,7 @@ jobs:
           git config --global user.name "John Doe"
           git config --global user.email johndoe@example.com
           git commit -m 'n/a'
-          git apply ../../bash.patch
+          git apply ../../2410.patch
       - name: Run unit tests
         run: npm run coverage:unit
   transpile:

bash.patch 2410.patchbash.patch renamed to 2410.patch

@@ -11,3 +11,16 @@ index 19fba6d..c1c57ce 100644
      .replace(/(?<=[:=])(~)(?=[\s+\-/0:=]|$)/gu, "\\$1")
      .replace(/([\t ])/gu, "\\$1");
  }
+diff --git a/src/internal/unix/busybox.js b/src/internal/unix/busybox.js
+index e61262f..0c91dc4 100644
+--- a/src/internal/unix/busybox.js
++++ b/src/internal/unix/busybox.js
+@@ -15,7 +15,7 @@ function escapeArg(arg) {
+     .replace(/\n/gu, " ")
+     .replace(/\\/gu, "\\\\")
+     .replace(/(?<=^|\s)([#~])/gu, "\\$1")
+-    .replace(/(["$&'()*;<>?`|])/gu, "\\$1")
++    .replace(/(["$&'()*;<>?`|[\]])/gu, "\\$1")
+     .replace(/([\t ])/gu, "\\$1");
+ }
+ 

test/unit/unix/bash.test.js

@@ -1,6 +1,6 @@
 /**
- * @overview Contains differential tests for the migration form standard regular
- * expressions to linear-time regular expressions in Bash.
+ * @overview Contains (additional) unit tests for the escaping functionality for
+ * the Bourne-again shell (Bash).
  * @license MIT
  */
 

test/unit/unix/busybox.test.js

@@ -0,0 +1,55 @@
+/**
+ * @overview Contains (additional) unit tests for the escaping functionality for
+ * the BusyBox shell.
+ * @license MIT
+ */
+
+import { testProp } from "@fast-check/ava";
+import * as fc from "fast-check";
+
+import * as old from "../../../node_modules/shescape-previous/src/internal/unix/busybox.js";
+import * as upd from "../../../src/internal/unix/busybox.js";
+
+const numRuns = 5_000_000;
+
+testProp(
+  "escape functionality is unchanged",
+  [fc.string()],
+  (t, arg) => {
+    const updFn = upd.getEscapeFunction();
+    const oldFn = old.getEscapeFunction();
+
+    const got = updFn(arg);
+    const want = oldFn(arg);
+    t.is(got, want);
+  },
+  { numRuns },
+);
+
+testProp(
+  "quote functionality is unchanged",
+  [fc.string()],
+  (t, arg) => {
+    const updFn = upd.getQuoteFunction();
+    const oldFn = old.getQuoteFunction();
+
+    const got = updFn[0](updFn[1](arg));
+    const want = oldFn[0](oldFn[1](arg));
+    t.is(got, want);
+  },
+  { numRuns },
+);
+
+testProp(
+  "flag protection functionality is unchanged",
+  [fc.string()],
+  (t, arg) => {
+    const updFn = upd.getFlagProtectionFunction();
+    const oldFn = old.getFlagProtectionFunction();
+
+    const got = updFn(arg);
+    const want = oldFn(arg);
+    t.is(got, want);
+  },
+  { numRuns },
+);

test/unit/win/cmd.test.js

@@ -1,6 +1,6 @@
 /**
- * @overview Contains differential tests for the migration form standard regular
- * expressions to linear-time regular expressions in CMD.
+ * @overview Contains (additional) unit tests for the escaping functionality for
+ * the the Windows Command Prompt.
  * @license MIT
  */