warn user that installation will fail if she doesn't have necessary w…

…rite permission

bin/ruby-install

@@ -18,6 +18,11 @@ fi
 
 init || exit $?
 
+if [[ ! -w "$install_dir" ]]; then
+	log "seems like you need necessary write permission on $install_dir"
+	exit 1
+fi
+
 if [[ $no_reinstall -eq 1 ]] && [[ -x "$install_dir/bin/ruby" ]]; then
 	log "Ruby is already installed into $install_dir"
 	exit

test/cli-tests/no_permission_warn_test.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+. ./test/helper.sh
+
+test_install_dir="$test_fixtures_dir/no_permission_warn_test"
+
+function setUp()
+{
+	mkdir -p $test_install_dir
+	chmod -w $test_install_dir
+}
+
+function test_no_install_when_write_permissions_lacking()
+{
+	local output="$(ruby-install --install-dir "$test_install_dir" ruby)"
+
+	assertEquals "did not return 0" 0 $?
+	assertTrue "did not print a message to STDOUT" \
+		'[[ "$output" == *"need necessary write permission"* ]]'
+}
+
+function tearDown()
+{
+	rm -rf "$test_install_dir"
+}
+
+SHUNIT_PARENT=$0 . $SHUNIT2