Shell: Add some tests for functions

Shell/Tests/function.sh

@@ -0,0 +1,26 @@
+#!/bin/sh
+
+# Syntax ok?
+fn() { echo $* }
+
+# Can we invoke that?
+test "$(fn 1)" = 1 || echo cannot invoke "'fn 1'" && exit 1
+test "$(fn 1 2)" = "1 2" || echo cannot invoke "'fn 1 2'" && exit 1
+
+# With explicit argument names?
+fn(a) { echo $a }
+
+# Can we invoke that?
+test "$(fn 1)" = 1 || echo cannot invoke "'fn 1'" with explicit names && exit 1
+test "$(fn 1 2)" = 1 || echo cannot invoke "'fn 1 2'" with explicit names and extra arguments && exit 1
+
+# Can it fail?
+if fn 2>/dev/null {
+    echo "'fn'" with an explicit argument is not failing with not enough args
+    exit 1
+}
+
+# $0 in function should be its name
+fn() { echo $0 }
+
+test "$(fn)" = fn || echo '$0' in function not equal to its name && exit 1