Added tests

test.sh

@@ -2,6 +2,31 @@
 #
 # Tests for the Pure Bash Bible.
 
+test_trim_string() {
+    result="$(trim_string "    Hello,    World    ")"
+    assert_equals "$result" "Hello,    World"
+}
+
+test_trim_all() {
+    result="$(trim_all "    Hello,    World    ")"
+    assert_equals "$result" "Hello, World"
+}
+
+test_lower() {
+    result="$(lower "HeLlO")"
+    assert_equals "$result" "hello"
+}
+
+test_upper() {
+    result="$(upper "HeLlO")"
+    assert_equals "$result" "HELLO"
+}
+
+test_trim_quotes() {
+    result="$(trim_quotes "\"te'st' 'str'ing\"")"
+    assert_equals "$result" "test string"
+}
+
 assert_equals() {
     # Test equality.
     local status
@@ -10,15 +35,14 @@ assert_equals() {
     [[ "$1" == "$2" ]] || { :>/tmp/err; return 1; } && return 0
 }
 
-test_trim() {
-    result="$(trim "    Hello,    World    ")"
-    assert_equals "$result" "Hello,    World"
-}
-
 main() {
     source <(awk '/```sh/{f=1;next}/```/{f=0}f' README.md) 2>/dev/null
 
-    test_trim
+    test_trim_string
+    test_trim_all
+    test_lower
+    test_upper
+    test_trim_quotes
 
     [[ -f /tmp/err ]] || exit 0 && { rm /tmp/err; exit 1; }
 }