From 985ac3b38175b6979bf3761c3d1d4a6f0a24ce2c Mon Sep 17 00:00:00 2001
From: Dorian Peron <dorianperon.i@gmail.com>
Date: Tue, 25 Feb 2025 01:14:31 +0100
Subject: [PATCH 1/2] test(expr): Add GNU tests to rust testsuite

---
 tests/by-util/test_expr.rs | 878 +++++++++++++++++++++++++++++++++++++
 1 file changed, 878 insertions(+)

diff --git a/tests/by-util/test_expr.rs b/tests/by-util/test_expr.rs
index a7f4b0cd9..aff5596da 100644
--- a/tests/by-util/test_expr.rs
+++ b/tests/by-util/test_expr.rs
@@ -3,6 +3,9 @@
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
 // spell-checker:ignore αbcdef ; (people) kkos
+// spell-checker:ignore aabcccd aabcd aabd abbbd abbcabc abbcac abbcbbbd abbcbd
+// spell-checker:ignore abbccd abcac acabc andand bigcmp bignum emptysub
+// spell-checker:ignore orempty oror
 
 use crate::common::util::TestScenario;
 
@@ -364,3 +367,878 @@ fn test_eager_evaluation() {
         .fails()
         .stderr_contains("division by zero");
 }
+
+/// Regroup the testcases of the GNU test expr.pl
+mod gnu_expr {
+    use crate::common::util::TestScenario;
+
+    #[test]
+    fn test_a() {
+        new_ucmd!()
+            .args(&["5", "+", "6"])
+            .succeeds()
+            .stdout_only("11\n");
+    }
+
+    #[test]
+    fn test_b() {
+        new_ucmd!()
+            .args(&["5", "-", "6"])
+            .succeeds()
+            .stdout_only("-1\n");
+    }
+
+    #[test]
+    fn test_c() {
+        new_ucmd!()
+            .args(&["5", "*", "6"])
+            .succeeds()
+            .stdout_only("30\n");
+    }
+
+    #[test]
+    fn test_d() {
+        new_ucmd!()
+            .args(&["100", "/", "6"])
+            .succeeds()
+            .stdout_only("16\n");
+    }
+
+    #[test]
+    fn test_e() {
+        new_ucmd!()
+            .args(&["100", "%", "6"])
+            .succeeds()
+            .stdout_only("4\n");
+    }
+
+    #[test]
+    fn test_f() {
+        new_ucmd!()
+            .args(&["3", "+", "-2"])
+            .succeeds()
+            .stdout_only("1\n");
+    }
+
+    #[test]
+    fn test_g() {
+        new_ucmd!()
+            .args(&["-2", "+", "-2"])
+            .succeeds()
+            .stdout_only("-4\n");
+    }
+
+    #[test]
+    fn test_opt1() {
+        new_ucmd!()
+            .args(&["--", "-11", "+", "12"])
+            .succeeds()
+            .stdout_only("1\n");
+    }
+
+    #[test]
+    fn test_opt2() {
+        new_ucmd!()
+            .args(&["-11", "+", "12"])
+            .succeeds()
+            .stdout_only("1\n");
+    }
+
+    #[test]
+    fn test_opt3() {
+        new_ucmd!()
+            .args(&["--", "-1", "+", "2"])
+            .succeeds()
+            .stdout_only("1\n");
+    }
+
+    #[test]
+    fn test_opt4() {
+        new_ucmd!()
+            .args(&["-1", "+", "2"])
+            .succeeds()
+            .stdout_only("1\n");
+    }
+
+    #[test]
+    fn test_opt5() {
+        new_ucmd!()
+            .args(&["--", "2", "+", "2"])
+            .succeeds()
+            .stdout_only("4\n");
+    }
+
+    #[test]
+    fn test_paren1() {
+        new_ucmd!()
+            .args(&["(", "100", "%", "6", ")"])
+            .succeeds()
+            .stdout_only("4\n");
+    }
+
+    #[test]
+    fn test_paren2() {
+        new_ucmd!()
+            .args(&["(", "100", "%", "6", ")", "-", "8"])
+            .succeeds()
+            .stdout_only("-4\n");
+    }
+
+    #[test]
+    fn test_paren3() {
+        new_ucmd!()
+            .args(&["9", "/", "(", "100", "%", "6", ")", "-", "8"])
+            .succeeds()
+            .stdout_only("-6\n");
+    }
+
+    #[test]
+    fn test_paren4() {
+        new_ucmd!()
+            .args(&["9", "/", "(", "(", "100", "%", "6", ")", "-", "8", ")"])
+            .succeeds()
+            .stdout_only("-2\n");
+    }
+
+    #[test]
+    fn test_paren5() {
+        new_ucmd!()
+            .args(&["9", "+", "(", "100", "%", "6", ")"])
+            .succeeds()
+            .stdout_only("13\n");
+    }
+
+    #[test]
+    fn test_0bang() {
+        new_ucmd!()
+            .args(&["00", "<", "0!"])
+            .fails()
+            .code_is(1)
+            .stdout_only("0\n");
+    }
+
+    #[test]
+    fn test_00() {
+        new_ucmd!()
+            .args(&["00"])
+            .fails()
+            .code_is(1)
+            .stdout_only("00\n");
+    }
+
+    #[test]
+    fn test_minus0() {
+        new_ucmd!()
+            .args(&["-0"])
+            .fails()
+            .code_is(1)
+            .stdout_only("-0\n");
+    }
+
+    #[test]
+    fn test_andand() {
+        new_ucmd!()
+            .args(&["0", "&", "1", "/", "0"])
+            .fails()
+            .code_is(1)
+            .stdout_only("0\n");
+    }
+
+    #[test]
+    fn test_oror() {
+        new_ucmd!()
+            .args(&["1", "|", "1", "/", "0"])
+            .succeeds()
+            .stdout_only("1\n");
+    }
+
+    #[test]
+    fn test_orempty() {
+        new_ucmd!()
+            .args(&["", "|", ""])
+            .fails()
+            .code_is(1)
+            .stdout_only("0\n");
+    }
+
+    #[test]
+    fn test_fail_a() {
+        new_ucmd!()
+            .args(&["3", "+", "-"])
+            .fails()
+            .code_is(2)
+            .no_stdout()
+            .stderr_contains("non-integer argument");
+    }
+
+    #[test]
+    fn test_bigcmp() {
+        new_ucmd!()
+            .args(&[
+                "--",
+                "-2417851639229258349412352",
+                "<",
+                "2417851639229258349412352",
+            ])
+            .succeeds()
+            .stdout_only("1\n");
+    }
+
+    #[ignore]
+    #[test]
+    fn test_anchor() {
+        new_ucmd!()
+            .args(&["a\nb", ":", "a$"])
+            .fails()
+            .code_is(1)
+            .stdout_only("0\n");
+    }
+
+    #[test]
+    fn test_emptysub() {
+        new_ucmd!()
+            .args(&["a", ":", "\\(b\\)*"])
+            .fails()
+            .code_is(1)
+            .stdout_only("\n");
+    }
+
+    #[test]
+    fn test_bre1() {
+        new_ucmd!()
+            .args(&["abc", ":", "a\\(b\\)c"])
+            .succeeds()
+            .stdout_only("b\n");
+    }
+
+    #[test]
+    fn test_bre2() {
+        new_ucmd!()
+            .args(&["a(", ":", "a("])
+            .succeeds()
+            .stdout_only("2\n");
+    }
+
+    #[test]
+    fn test_bre3() {
+        new_ucmd!()
+            .args(&["_", ":", "a\\("])
+            .fails_with_code(2)
+            .no_stdout()
+            .stderr_contains("Unmatched ( or \\(");
+    }
+
+    #[test]
+    fn test_bre4() {
+        new_ucmd!()
+            .args(&["_", ":", "a\\(b"])
+            .fails_with_code(2)
+            .no_stdout()
+            .stderr_contains("Unmatched ( or \\(");
+    }
+
+    #[test]
+    fn test_bre5() {
+        new_ucmd!()
+            .args(&["a(b", ":", "a(b"])
+            .succeeds()
+            .stdout_only("3\n");
+    }
+
+    #[test]
+    fn test_bre6() {
+        new_ucmd!()
+            .args(&["a)", ":", "a)"])
+            .succeeds()
+            .stdout_only("2\n");
+    }
+
+    #[test]
+    fn test_bre7() {
+        new_ucmd!()
+            .args(&["_", ":", "a\\)"])
+            .fails_with_code(2)
+            .stderr_contains("Unmatched ) or \\)");
+    }
+
+    #[test]
+    fn test_bre8() {
+        new_ucmd!()
+            .args(&["_", ":", "\\)"])
+            .fails_with_code(2)
+            .stderr_contains("Unmatched ) or \\)");
+    }
+
+    #[test]
+    fn test_bre9() {
+        new_ucmd!()
+            .args(&["ab", ":", "a\\(\\)b"])
+            .fails_with_code(1)
+            .stdout_only("\n");
+    }
+
+    #[ignore]
+    #[test]
+    fn test_bre10() {
+        new_ucmd!()
+            .args(&["a^b", ":", "a^b"])
+            .succeeds()
+            .stdout_only("3\n");
+    }
+
+    #[ignore]
+    #[test]
+    fn test_bre11() {
+        new_ucmd!()
+            .args(&["a$b", ":", "a$b"])
+            .succeeds()
+            .stdout_only("3\n");
+    }
+
+    #[test]
+    fn test_bre12() {
+        new_ucmd!()
+            .args(&["", ":", "\\($\\)\\(^\\)"])
+            .fails_with_code(1)
+            .stdout_only("\n");
+    }
+
+    #[test]
+    fn test_bre13() {
+        new_ucmd!()
+            .args(&["b", ":", "a*\\(b$\\)c*"])
+            .succeeds()
+            .stdout_only("b\n");
+    }
+
+    #[test]
+    fn test_bre14() {
+        new_ucmd!()
+            .args(&["X|", ":", "X\\(|\\)", ":", "(", "X|", ":", "X\\(|\\)", ")"])
+            .succeeds()
+            .stdout_only("1\n");
+    }
+
+    #[test]
+    fn test_bre15() {
+        new_ucmd!()
+            .args(&["X*", ":", "X\\(*\\)", ":", "(", "X*", ":", "X\\(*\\)", ")"])
+            .succeeds()
+            .stdout_only("1\n");
+    }
+
+    #[test]
+    fn test_bre16() {
+        new_ucmd!()
+            .args(&["abc", ":", "\\(\\)"])
+            .fails_with_code(1)
+            .stdout_only("\n");
+    }
+
+    #[ignore]
+    #[test]
+    fn test_bre17() {
+        new_ucmd!()
+            .args(&["{1}a", ":", "\\(\\{1\\}a\\)"])
+            .succeeds()
+            .stdout_only("{1}a\n");
+    }
+
+    #[ignore]
+    #[test]
+    fn test_bre18() {
+        new_ucmd!()
+            .args(&["X*", ":", "X\\(*\\)", ":", "^*"])
+            .succeeds()
+            .stdout_only("1\n");
+    }
+
+    #[ignore]
+    #[test]
+    fn test_bre19() {
+        new_ucmd!()
+            .args(&["{1}", ":", "\\{1\\}"])
+            .succeeds()
+            .stdout_only("3\n");
+    }
+
+    #[test]
+    fn test_bre20() {
+        new_ucmd!()
+            .args(&["{", ":", "{"])
+            .succeeds()
+            .stdout_only("1\n");
+    }
+
+    #[test]
+    fn test_bre21() {
+        new_ucmd!()
+            .args(&["abbcbd", ":", "a\\(b*\\)c\\1d"])
+            .fails_with_code(1)
+            .stdout_only("\n");
+    }
+
+    #[test]
+    fn test_bre22() {
+        new_ucmd!()
+            .args(&["abbcbbbd", ":", "a\\(b*\\)c\\1d"])
+            .fails_with_code(1)
+            .stdout_only("\n");
+    }
+
+    #[test]
+    fn test_bre23() {
+        new_ucmd!()
+            .args(&["abc", ":", "\\(.\\)\\1"])
+            .fails_with_code(1)
+            .stdout_only("\n");
+    }
+
+    #[test]
+    fn test_bre24() {
+        new_ucmd!()
+            .args(&["abbccd", ":", "a\\(\\([bc]\\)\\2\\)*d"])
+            .succeeds()
+            .stdout_only("cc\n");
+    }
+
+    #[test]
+    fn test_bre25() {
+        new_ucmd!()
+            .args(&["abbcbd", ":", "a\\(\\([bc]\\)\\2\\)*d"])
+            .fails_with_code(1)
+            .stdout_only("\n");
+    }
+
+    #[test]
+    fn test_bre26() {
+        new_ucmd!()
+            .args(&["abbbd", ":", "a\\(\\(b\\)*\\2\\)*d"])
+            .succeeds()
+            .stdout_only("bbb\n");
+    }
+
+    #[test]
+    fn test_bre27() {
+        new_ucmd!()
+            .args(&["aabcd", ":", "\\(a\\)\\1bcd"])
+            .succeeds()
+            .stdout_only("a\n");
+    }
+
+    #[test]
+    fn test_bre28() {
+        new_ucmd!()
+            .args(&["aabcd", ":", "\\(a\\)\\1bc*d"])
+            .succeeds()
+            .stdout_only("a\n");
+    }
+
+    #[test]
+    fn test_bre29() {
+        new_ucmd!()
+            .args(&["aabd", ":", "\\(a\\)\\1bc*d"])
+            .succeeds()
+            .stdout_only("a\n");
+    }
+
+    #[test]
+    fn test_bre30() {
+        new_ucmd!()
+            .args(&["aabcccd", ":", "\\(a\\)\\1bc*d"])
+            .succeeds()
+            .stdout_only("a\n");
+    }
+
+    #[test]
+    fn test_bre31() {
+        new_ucmd!()
+            .args(&["aabcccd", ":", "\\(a\\)\\1bc*[ce]d"])
+            .succeeds()
+            .stdout_only("a\n");
+    }
+
+    #[test]
+    fn test_bre32() {
+        new_ucmd!()
+            .args(&["aabcccd", ":", "\\(a\\)\\1b\\(c\\)*cd"])
+            .succeeds()
+            .stdout_only("a\n");
+    }
+
+    #[test]
+    fn test_bre33() {
+        new_ucmd!()
+            .args(&["a*b", ":", "a\\(*\\)b"])
+            .succeeds()
+            .stdout_only("*\n");
+    }
+
+    #[test]
+    fn test_bre34() {
+        new_ucmd!()
+            .args(&["ab", ":", "a\\(**\\)b"])
+            .fails_with_code(1)
+            .stdout_only("\n");
+    }
+
+    #[test]
+    fn test_bre35() {
+        new_ucmd!()
+            .args(&["ab", ":", "a\\(***\\)b"])
+            .fails_with_code(1)
+            .stdout_only("\n");
+    }
+
+    #[test]
+    fn test_bre36() {
+        new_ucmd!()
+            .args(&["*a", ":", "*a"])
+            .succeeds()
+            .stdout_only("2\n");
+    }
+
+    #[test]
+    fn test_bre37() {
+        new_ucmd!()
+            .args(&["a", ":", "**a"])
+            .succeeds()
+            .stdout_only("1\n");
+    }
+
+    #[test]
+    fn test_bre38() {
+        new_ucmd!()
+            .args(&["a", ":", "***a"])
+            .succeeds()
+            .stdout_only("1\n");
+    }
+
+    #[test]
+    fn test_bre39() {
+        new_ucmd!()
+            .args(&["ab", ":", "a\\{1\\}b"])
+            .succeeds()
+            .stdout_only("2\n");
+    }
+
+    #[test]
+    fn test_bre40() {
+        new_ucmd!()
+            .args(&["ab", ":", "a\\{1,\\}b"])
+            .succeeds()
+            .stdout_only("2\n");
+    }
+
+    #[test]
+    fn test_bre41() {
+        new_ucmd!()
+            .args(&["aab", ":", "a\\{1,2\\}b"])
+            .succeeds()
+            .stdout_only("3\n");
+    }
+
+    #[test]
+    fn test_bre42() {
+        new_ucmd!()
+            .args(&["_", ":", "a\\{1"])
+            .fails_with_code(2)
+            .no_stdout()
+            .stderr_contains("Unmatched \\{");
+    }
+
+    #[test]
+    fn test_bre43() {
+        new_ucmd!()
+            .args(&["_", ":", "a\\{1a"])
+            .fails_with_code(2)
+            .no_stdout()
+            .stderr_contains("Unmatched \\{");
+    }
+
+    #[test]
+    fn test_bre44() {
+        new_ucmd!()
+            .args(&["_", ":", "a\\{1a\\}"])
+            .fails_with_code(2)
+            .no_stdout()
+            .stderr_contains("Invalid content of \\{\\}");
+    }
+
+    #[ignore]
+    #[test]
+    fn test_bre45() {
+        new_ucmd!()
+            .args(&["a", ":", "a\\{,2\\}"])
+            .succeeds()
+            .stdout_only("1\n");
+    }
+
+    #[ignore]
+    #[test]
+    fn test_bre46() {
+        new_ucmd!()
+            .args(&["a", ":", "a\\{,\\}"])
+            .succeeds()
+            .stdout_only("1\n");
+    }
+
+    #[test]
+    fn test_bre47() {
+        new_ucmd!()
+            .args(&["_", ":", "a\\{1,x\\}"])
+            .fails_with_code(2)
+            .no_stdout()
+            .stderr_contains("Invalid content of \\{\\}");
+    }
+
+    #[test]
+    fn test_bre48() {
+        new_ucmd!()
+            .args(&["_", ":", "a\\{1,x"])
+            .fails_with_code(2)
+            .no_stdout()
+            .stderr_contains("Unmatched \\{");
+    }
+
+    #[test]
+    fn test_bre49() {
+        new_ucmd!()
+            .args(&["_", ":", "a\\{32768\\}"])
+            .fails_with_code(2)
+            .no_stdout()
+            .stderr_contains("Invalid content of \\{\\}");
+    }
+
+    #[test]
+    fn test_bre50() {
+        new_ucmd!()
+            .args(&["_", ":", "a\\{1,0\\}"])
+            .fails_with_code(2)
+            .no_stdout()
+            .stderr_contains("Invalid content of \\{\\}");
+    }
+
+    #[test]
+    fn test_bre51() {
+        new_ucmd!()
+            .args(&["acabc", ":", ".*ab\\{0,0\\}c"])
+            .succeeds()
+            .stdout_only("2\n");
+    }
+
+    #[test]
+    fn test_bre52() {
+        new_ucmd!()
+            .args(&["abcac", ":", "ab\\{0,1\\}c"])
+            .succeeds()
+            .stdout_only("3\n");
+    }
+
+    #[test]
+    fn test_bre53() {
+        new_ucmd!()
+            .args(&["abbcac", ":", "ab\\{0,3\\}c"])
+            .succeeds()
+            .stdout_only("4\n");
+    }
+
+    #[test]
+    fn test_bre54() {
+        new_ucmd!()
+            .args(&["abcac", ":", ".*ab\\{1,1\\}c"])
+            .succeeds()
+            .stdout_only("3\n");
+    }
+
+    #[test]
+    fn test_bre55() {
+        new_ucmd!()
+            .args(&["abcac", ":", ".*ab\\{1,3\\}c"])
+            .succeeds()
+            .stdout_only("3\n");
+    }
+
+    #[test]
+    fn test_bre56() {
+        new_ucmd!()
+            .args(&["abbcabc", ":", ".*ab\\{2,2\\}c"])
+            .succeeds()
+            .stdout_only("4\n");
+    }
+
+    #[test]
+    fn test_bre57() {
+        new_ucmd!()
+            .args(&["abbcabc", ":", ".*ab\\{2,4\\}c"])
+            .succeeds()
+            .stdout_only("4\n");
+    }
+
+    #[test]
+    fn test_bre58() {
+        new_ucmd!()
+            .args(&["aa", ":", "a\\{1\\}\\{1\\}"])
+            .succeeds()
+            .stdout_only("1\n");
+    }
+
+    #[test]
+    fn test_bre59() {
+        new_ucmd!()
+            .args(&["aa", ":", "a*\\{1\\}"])
+            .succeeds()
+            .stdout_only("2\n");
+    }
+
+    #[test]
+    fn test_bre60() {
+        new_ucmd!()
+            .args(&["aa", ":", "a\\{1\\}*"])
+            .succeeds()
+            .stdout_only("2\n");
+    }
+
+    #[test]
+    fn test_bre61() {
+        new_ucmd!()
+            .args(&["acd", ":", "a\\(b\\)?c\\1d"])
+            .fails_with_code(1)
+            .stdout_only("\n");
+    }
+
+    #[test]
+    fn test_bre62() {
+        new_ucmd!()
+            .args(&["--", "-5", ":", "-\\{0,1\\}[0-9]*$"])
+            .succeeds()
+            .stdout_only("2\n");
+    }
+
+    #[test]
+    fn test_fail_c() {
+        new_ucmd!()
+            .args::<&str>(&[])
+            .fails_with_code(2)
+            .no_stdout()
+            .stderr_contains("missing operand")
+            .stderr_contains("Try")
+            .stderr_contains("for more information");
+    }
+
+    const BIG: &str = "98782897298723498732987928734";
+    const BIG_P1: &str = "98782897298723498732987928735";
+    const BIG_SUM: &str = "197565794597446997465975857469";
+    const BIG_PROD: &str = "9758060798730154302876482828124348356960410232492450771490";
+
+    #[test]
+    fn test_bignum_add() {
+        new_ucmd!()
+            .args(&[BIG, "+", "1"])
+            .succeeds()
+            .stdout_only(format!("{BIG_P1}\n"));
+    }
+
+    #[test]
+    fn test_bignum_add1() {
+        new_ucmd!()
+            .args(&[BIG, "+", BIG_P1])
+            .succeeds()
+            .stdout_only(format!("{BIG_SUM}\n"));
+    }
+
+    #[test]
+    fn test_bignum_sub() {
+        new_ucmd!()
+            .args(&[BIG_P1, "-", "1"])
+            .succeeds()
+            .stdout_only(format!("{BIG}\n"));
+    }
+
+    #[test]
+    fn test_bignum_sub1() {
+        new_ucmd!()
+            .args(&[BIG_SUM, "-", BIG])
+            .succeeds()
+            .stdout_only(format!("{BIG_P1}\n"));
+    }
+
+    #[test]
+    fn test_bignum_mul() {
+        new_ucmd!()
+            .args(&[BIG_P1, "*", BIG])
+            .succeeds()
+            .stdout_only(format!("{BIG_PROD}\n"));
+    }
+
+    #[test]
+    fn test_bignum_div() {
+        new_ucmd!()
+            .args(&[BIG_PROD, "/", BIG])
+            .succeeds()
+            .stdout_only(format!("{BIG_P1}\n"));
+    }
+
+    #[test]
+    fn test_se0() {
+        new_ucmd!()
+            .args(&["9", "9"])
+            .fails_with_code(2)
+            .no_stdout()
+            .stderr_contains("syntax error: unexpected argument '9'");
+    }
+
+    #[test]
+    fn test_se1() {
+        new_ucmd!()
+            .args(&["2", "a"])
+            .fails_with_code(2)
+            .no_stdout()
+            .stderr_contains("syntax error: unexpected argument 'a'");
+    }
+
+    #[test]
+    fn test_se2() {
+        new_ucmd!()
+            .args(&["2", "+"])
+            .fails_with_code(2)
+            .no_stdout()
+            .stderr_contains("syntax error: missing argument after '+'");
+    }
+
+    #[test]
+    fn test_se3() {
+        new_ucmd!()
+            .args(&["2", ":"])
+            .fails_with_code(2)
+            .no_stdout()
+            .stderr_contains("syntax error: missing argument after ':'");
+    }
+
+    #[test]
+    fn test_se4() {
+        new_ucmd!()
+            .args(&["length"])
+            .fails_with_code(2)
+            .no_stdout()
+            .stderr_contains("syntax error: missing argument after 'length'");
+    }
+
+    #[test]
+    fn test_se5() {
+        new_ucmd!()
+            .args(&["(", "2"])
+            .fails_with_code(2)
+            .no_stdout()
+            .stderr_contains("syntax error: expecting ')' after '2'");
+    }
+
+    #[test]
+    fn test_se6() {
+        new_ucmd!()
+            .args(&["(", "2", "a"])
+            .fails_with_code(2)
+            .no_stdout()
+            .stderr_contains("syntax error: expecting ')' instead of 'a'");
+    }
+}

From a9d8eed217b463abf18c32570b621b09acec4286 Mon Sep 17 00:00:00 2001
From: Dorian Peron <dorianperon.i@gmail.com>
Date: Tue, 25 Feb 2025 01:23:28 +0100
Subject: [PATCH 2/2] expr: Remove useless arg in enum variant

---
 src/uu/expr/src/expr.rs        |  4 ++--
 src/uu/expr/src/syntax_tree.rs | 18 +++++++++---------
 tests/by-util/test_expr.rs     |  2 +-
 3 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/src/uu/expr/src/expr.rs b/src/uu/expr/src/expr.rs
index 99ae27e4a..bfa647902 100644
--- a/src/uu/expr/src/expr.rs
+++ b/src/uu/expr/src/expr.rs
@@ -48,8 +48,8 @@ pub enum ExprError {
     UnmatchedOpeningBrace,
     #[error("Unmatched ) or \\}}")]
     UnmatchedClosingBrace,
-    #[error("Invalid content of {0}")]
-    InvalidContent(String),
+    #[error("Invalid content of \\{{\\}}")]
+    InvalidBracketContent,
 }
 
 impl UError for ExprError {
diff --git a/src/uu/expr/src/syntax_tree.rs b/src/uu/expr/src/syntax_tree.rs
index 149f24bb2..d7ac02ca3 100644
--- a/src/uu/expr/src/syntax_tree.rs
+++ b/src/uu/expr/src/syntax_tree.rs
@@ -264,7 +264,7 @@ fn check_posix_regex_errors(pattern: &str) -> ExprResult<()> {
         (true, true, false) => Ok(()),
         (_, false, _) => Err(ExprError::UnmatchedOpeningBrace),
         (false, _, _) => Err(ExprError::UnmatchedOpeningParenthesis),
-        (true, true, true) => Err(ExprError::InvalidContent(r"\{\}".to_string())),
+        (true, true, true) => Err(ExprError::InvalidBracketContent),
     }
 }
 
@@ -601,7 +601,7 @@ pub fn is_truthy(s: &NumOrStr) -> bool {
 #[cfg(test)]
 mod test {
     use crate::ExprError;
-    use crate::ExprError::InvalidContent;
+    use crate::ExprError::InvalidBracketContent;
 
     use super::{check_posix_regex_errors, AstNode, BinOp, NumericOp, RelationOp, StringOp};
 
@@ -795,7 +795,7 @@ mod test {
     fn check_regex_empty_repeating_pattern() {
         assert_eq!(
             check_posix_regex_errors("ab\\{\\}"),
-            Err(InvalidContent(r"\{\}".to_string()))
+            Err(InvalidBracketContent)
         )
     }
 
@@ -804,27 +804,27 @@ mod test {
         assert_eq!(
             // out of order
             check_posix_regex_errors("ab\\{1,0\\}"),
-            Err(InvalidContent(r"\{\}".to_string()))
+            Err(InvalidBracketContent)
         );
         assert_eq!(
             check_posix_regex_errors("ab\\{1,a\\}"),
-            Err(InvalidContent(r"\{\}".to_string()))
+            Err(InvalidBracketContent)
         );
         assert_eq!(
             check_posix_regex_errors("ab\\{a,3\\}"),
-            Err(InvalidContent(r"\{\}".to_string()))
+            Err(InvalidBracketContent)
         );
         assert_eq!(
             check_posix_regex_errors("ab\\{a,b\\}"),
-            Err(InvalidContent(r"\{\}".to_string()))
+            Err(InvalidBracketContent)
         );
         assert_eq!(
             check_posix_regex_errors("ab\\{a,\\}"),
-            Err(InvalidContent(r"\{\}".to_string()))
+            Err(InvalidBracketContent)
         );
         assert_eq!(
             check_posix_regex_errors("ab\\{,b\\}"),
-            Err(InvalidContent(r"\{\}".to_string()))
+            Err(InvalidBracketContent)
         );
     }
 }
diff --git a/tests/by-util/test_expr.rs b/tests/by-util/test_expr.rs
index aff5596da..ced4c3bbb 100644
--- a/tests/by-util/test_expr.rs
+++ b/tests/by-util/test_expr.rs
@@ -677,7 +677,7 @@ mod gnu_expr {
             .stdout_only("\n");
     }
 
-    #[ignore]
+    #[ignore = "rust-onig bug, see https://github.com/rust-onig/rust-onig/issues/188"]
     #[test]
     fn test_bre10() {
         new_ucmd!()