d881a2e52e
This also provides a SetPrepareCmd hook for tests to be able to define stubs for commands that are supposed to be run
59 lines
1.3 KiB
Go
59 lines
1.3 KiB
Go
package utils
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import (
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"bytes"
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"fmt"
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"os/exec"
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"strings"
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)
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// Runnable is typically an exec.Cmd or its stub in tests
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type Runnable interface {
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Output() ([]byte, error)
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Run() error
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}
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// PrepareCmd extends exec.Cmd with extra error reporting features and provides a
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// hook to stub command execution in tests
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var PrepareCmd = func(cmd *exec.Cmd) Runnable {
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return &cmdWithStderr{cmd}
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}
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// SetPrepareCmd overrides PrepareCmd and returns a func to revert it back
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func SetPrepareCmd(fn func(*exec.Cmd) Runnable) func() {
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origPrepare := PrepareCmd
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PrepareCmd = fn
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return func() {
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PrepareCmd = origPrepare
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}
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}
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// cmdWithStderr augments Output() by adding stderr to the error message
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type cmdWithStderr struct {
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*exec.Cmd
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}
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func (c cmdWithStderr) Output() ([]byte, error) {
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errStream := &bytes.Buffer{}
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c.Cmd.Stderr = errStream
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out, err := c.Cmd.Output()
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if err != nil {
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err = &CmdError{errStream, c.Cmd.Args, err}
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}
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return out, err
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}
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// CmdError provides more visibility into why an exec.Cmd had failed
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type CmdError struct {
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Stderr *bytes.Buffer
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Args []string
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Err error
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}
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func (e CmdError) Error() string {
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msg := e.Stderr.String()
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if msg != "" && !strings.HasSuffix(msg, "\n") {
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msg += "\n"
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}
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return fmt.Sprintf("%s%s: %s", msg, e.Args[0], e.Err)
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}
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