t0014: test shadowing of aliases for a sample of builtins

The previous commit added tests for shadowing deprecated builtins.
Let’s make the test suite more complete by exercising a sample of
the builtins and in turn test the documentation for git-config(1):

    To avoid confusion and troubles with script usage, aliases that hide
    existing Git commands are ignored except for deprecated commands.

Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t0014-alias.sh

@@ -95,4 +95,21 @@ test_expect_success 'can alias-shadow via two deprecated builtins' '
 	test_cmp expect actual
 '
 
+cannot_alias_regular_builtin () {
+	cmd="$1" &&
+	# some git(1) commands will fail... (see above)
+	test_might_fail git "$cmd" -h >expect &&
+	test_file_not_empty expect &&
+	test_might_fail git -c alias."$cmd"=status "$cmd" -h >actual &&
+	test_cmp expect actual
+}
+
+test_expect_success 'cannot alias-shadow a sample of regular builtins' '
+	for cmd in grep check-ref-format interpret-trailers \
+		checkout-index fast-import diagnose rev-list prune
+	do
+		cannot_alias_regular_builtin "$cmd" || return 1
+	done
+'
+
 test_done