Shell: Add tests for slices

Author: https://github.com/alimpfard
Commit: https://github.com/SerenityOS/serenity/commit/2efa17184d1
Pull-request: https://github.com/SerenityOS/serenity/pull/5749

Userland/Shell/Tests/slice.sh

@@ -0,0 +1,73 @@
+#!/bin/sh
+
+source $(dirname "$0")/test-commons.inc
+
+# can we use [0] as a bareword still?
+if not test [0] = "[0]" {
+    fail cannot use '[0]' as a bareword anymore
+}
+
+# can we use [0,2] as a bareword still?
+if not test [0,2] = "[0,2]" {
+    fail cannot use '[0,2]' as a bareword anymore
+}
+
+# can we use [0..2] as a bareword still?
+if not test [0..2] = "[0..2]" {
+    fail cannot use '[0..2]' as a bareword anymore
+}
+
+# Lists
+x=(1 2 3)
+if not test $x[0] -eq 1 {
+    fail invalid first element
+}
+
+if not test $x[1] -eq 2 {
+    fail invalid second element
+}
+
+if not test $x[-1] -eq 3 {
+    fail invalid first-from-end element
+}
+
+if not test $x[-2] -eq 2 {
+    fail invalid second-from-end element
+}
+
+## Multiple indices
+if not test "$x[1,2]" = "2 3" {
+    fail invalid multi-select '(1, 2)'
+}
+
+if not test "$x[0..2]" = "1 2 3" {
+    fail invalid multi-select with range '[0..2]'
+}
+
+# Strings
+x="Well Hello Friends!"
+if not test $x[0] = W {
+    fail invalid string first element
+}
+
+if not test $x[1] = e {
+    fail invalid string second element
+}
+
+if not test $x[-1] = '!' {
+    fail invalid string first-from-end element
+}
+
+if not test $x[-2] = 's' {
+    fail invalid string second-from-end element
+}
+
+if not test $x[0,5,11,-1] = 'WHF!' {
+    fail invalid string multi-select
+}
+
+if not test $x[5..9] = "Hello" {
+    fail invalid string multi-select with range '[5..9]'
+}
+
+pass