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Add package exec
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‎exec/exec.go

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/*
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* This file is part of arduino-create-agent.
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*
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* arduino-create-agent is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* As a special exception, you may use this file as part of a free software
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* library without restriction. Specifically, if other files instantiate
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* templates or use macros or inline functions from this file, or you compile
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* this file and link it with other files to produce an executable, this
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* file does not by itself cause the resulting executable to be covered by
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* the GNU General Public License. This exception does not however
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* invalidate any other reasons why the executable file might be covered by
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* the GNU General Public License.
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*
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* Copyright 2017 BCMI LABS SA (http://www.arduino.cc/)
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*/
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// Package exec is just syntactic sugar over os/exec. Allows to execute predefined
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// parametric commands in a safe way
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//
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// Usage:
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// cmd := exec.Command{
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// Pattern: "echo {interpolate.string}",
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// Params: []string{"interpolate.string"},
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// }
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// opts := map[string]string{"interpolate.string": "hello world"}
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// stdout, stderr, err := exec.Local(cmd, opts)
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// fmt.Println(err) // nil
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// out, _ := ioutil.ReadAll(stdout)
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// stdout.Close()
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// stderr.Close()
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// fmt.Println(string(out)) // hello world
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package exec
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import (
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"io"
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"os/exec"
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"strings"
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shellwords "github.com/mattn/go-shellwords"
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"github.com/pkg/errors"
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)
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// Command is a parametric command that can executed on the machine
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type Command struct {
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// Pattern is the commandline that will be safely interpolated with the parameters
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Pattern string
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// Params contains a list of parameters that can be safely interpolated in the pattern
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Params []string
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}
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// Interpolate substitutes the params with the corresponding options
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func (cmd Command) Interpolate(opts map[string]string) (interpolated []string, err error) {
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pattern := cmd.Pattern
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for key, value := range opts {
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pattern = strings.Replace(pattern, "{"+key+"}", value, -1)
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}
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z, err := shellwords.Parse(pattern)
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if err != nil {
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return nil, err
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}
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return z, nil
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}
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// Local executes a command on the local machine, interpolating the command with the
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// given options
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func Local(c Command, opts map[string]string) (stdout, stderr io.ReadCloser, err error) {
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// interpolate
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inter, err := c.Interpolate(opts)
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if err != nil {
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return nil, nil, errors.Wrapf(err, "interpolate")
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}
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// create command
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executable, args := inter[0], inter[1:]
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cmd := exec.Command(executable, args...)
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stdout, err = cmd.StdoutPipe()
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if err != nil {
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return nil, nil, errors.Wrapf(err, "retrieve output")
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}
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stderr, err = cmd.StderrPipe()
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if err != nil {
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return nil, nil, errors.Wrapf(err, "retrieve output")
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}
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err = cmd.Start()
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if err != nil {
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return nil, nil, err
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}
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return stdout, stderr, nil
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}

‎exec/exec_test.go

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/*
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* This file is part of arduino-create-agent.
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*
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* arduino-create-agent is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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* As a special exception, you may use this file as part of a free software
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* library without restriction. Specifically, if other files instantiate
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* templates or use macros or inline functions from this file, or you compile
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* this file and link it with other files to produce an executable, this
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* file does not by itself cause the resulting executable to be covered by
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* the GNU General Public License. This exception does not however
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* invalidate any other reasons why the executable file might be covered by
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* the GNU General Public License.
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*
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* Copyright 2017 BCMI LABS SA (http://www.arduino.cc/)
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*/
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package exec_test
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import (
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"errors"
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"fmt"
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"io/ioutil"
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"strings"
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"testing"
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"github.com/arduino/arduino-create-agent/exec"
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)
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func Example() {
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cmd := exec.Command{
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Pattern: "echo {interpolate.string}",
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Params: []string{"interpolate.string"},
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}
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opts := map[string]string{"interpolate.string": "hello world"}
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stdout, stderr, err := exec.Local(cmd, opts)
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fmt.Println(err) // nil
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out, _ := ioutil.ReadAll(stdout)
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stdout.Close()
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stderr.Close()
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fmt.Println(string(out)) // hello world
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// Output:
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// <nil>
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// hello world
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}
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func TestLocal(t *testing.T) {
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cases := []struct {
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ID string
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Pattern string
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Params []string
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Options map[string]string
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ExpStdout string
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ExpStderr string
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ExpErr error
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}{
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{
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"command not found",
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"foo",
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nil,
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nil,
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"",
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"",
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errors.New(`exec: "foo": executable file not found in $PATH`),
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},
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{
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"error",
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"foo '",
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nil,
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nil,
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"",
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"",
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errors.New("interpolate: invalid command line string"),
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},
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{
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"hello world",
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"echo {interpolate.string}",
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[]string{"interpolate.string"},
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map[string]string{
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"interpolate.string": "hello world",
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"ignored": "ignored",
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},
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"hello world",
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"",
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nil,
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},
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{
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"inject ; to perform other commands has no effect",
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"echo {interpolate.string}",
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[]string{"interpolate.string"},
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map[string]string{
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"interpolate.string": "hello world; ls",
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"ignored": "ignored",
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},
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"hello world",
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"",
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nil,
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},
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{
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"bash expansion do not work",
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"echo {interpolate.string}",
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[]string{"interpolate.string"},
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map[string]string{
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"interpolate.string": "`date`",
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"ignored": "ignored",
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},
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"`date`",
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"",
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nil,
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},
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{
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"env vars do not work",
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"echo {interpolate.string}",
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[]string{"interpolate.string"},
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map[string]string{
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"interpolate.string": "$USER",
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"ignored": "ignored",
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},
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"$USER",
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"",
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nil,
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},
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{
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"return stderr",
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"ls /notexist",
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[]string{"interpolate.string"},
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map[string]string{
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"interpolate.string": "$USER",
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"ignored": "ignored",
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},
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"",
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"ls: cannot access '/notexist': No such file or directory",
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nil,
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},
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}
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for _, tc := range cases {
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t.Run(fmt.Sprintf("%s", tc.ID), func(t *testing.T) {
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command := exec.Command{
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Pattern: tc.Pattern,
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Params: tc.Params,
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}
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stdout, stderr, e := exec.Local(command, tc.Options)
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if !errEq(e, tc.ExpErr) {
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t.Errorf("expected e to be '%s', was '%s'", tc.ExpErr, e)
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return
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}
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if e != nil {
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return
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}
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if stdout == nil || stderr == nil {
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t.Errorf("stdout and stderr should not be nil")
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return
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}
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out, _ := ioutil.ReadAll(stdout)
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stdout.Close()
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if strings.TrimSpace(string(out)) != tc.ExpStdout {
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t.Errorf("expected stdout to be '%s', was '%s'", tc.ExpStdout, out)
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}
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err, _ := ioutil.ReadAll(stderr)
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stderr.Close()
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if strings.TrimSpace(string(err)) != tc.ExpStderr {
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t.Errorf("expected stderr to be '%s', was '%s'", tc.ExpStderr, err)
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}
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})
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}
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}
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func errEq(err1, err2 error) bool {
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return fmt.Sprintf("%s", err1) == fmt.Sprintf("%s", err2)
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}

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