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chore: Add a helper function for executing commands (starship#660)
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andytom authored and matchai committed Nov 27, 2019
1 parent 91d6df3 commit f5bbaef
Showing 1 changed file with 95 additions and 0 deletions.
95 changes: 95 additions & 0 deletions src/utils.rs
Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
use std::fs::File;
use std::io::{Read, Result};
use std::path::Path;
use std::process::Command;

/// Return the string contents of a file
pub fn read_file<P: AsRef<Path>>(file_name: P) -> Result<String> {
Expand All @@ -10,3 +11,97 @@ pub fn read_file<P: AsRef<Path>>(file_name: P) -> Result<String> {
file.read_to_string(&mut data)?;
Ok(data)
}

#[derive(Debug)]
pub struct CommandOutput {
pub stdout: String,
pub stderr: String,
}

impl PartialEq for CommandOutput {
fn eq(&self, other: &Self) -> bool {
self.stdout == other.stdout && self.stderr == other.stderr
}
}

/// Execute a command and return the output on stdout and stderr if sucessful
pub fn exec_cmd(cmd: &str, args: &[&str]) -> Option<CommandOutput> {
log::trace!("Executing command '{:?}' with args '{:?}'", cmd, args);
match Command::new(cmd).args(args).output() {
Ok(output) => {
let stdout_string = String::from_utf8(output.stdout).unwrap();
let stderr_string = String::from_utf8(output.stderr).unwrap();

if !output.status.success() {
log::trace!("Non-zero exit code '{:?}'", output.status.code());
log::trace!("stdout: {}", stdout_string);
log::trace!("stderr: {}", stderr_string);
return None;
}

Some(CommandOutput {
stdout: stdout_string,
stderr: stderr_string,
})
}
Err(_) => None,
}
}

#[cfg(test)]
#[cfg(not(windows))] // While the exec_cmd should work on Windows these tests assume a Unix-like environment.
mod tests {
use super::*;

#[test]
fn exec_no_output() {
let result = exec_cmd("true", &[]);
let expected = Some(CommandOutput {
stdout: String::from(""),
stderr: String::from(""),
});

assert_eq!(result, expected)
}

#[test]
fn exec_with_output_stdout() {
let result = exec_cmd("/bin/echo", &["-n", "hello"]);
let expected = Some(CommandOutput {
stdout: String::from("hello"),
stderr: String::from(""),
});

assert_eq!(result, expected)
}

#[test]
fn exec_with_output_stderr() {
let result = exec_cmd("/bin/sh", &["-c", "echo hello >&2"]);
let expected = Some(CommandOutput {
stdout: String::from(""),
stderr: String::from("hello\n"),
});

assert_eq!(result, expected)
}

#[test]
fn exec_with_output_both() {
let result = exec_cmd("/bin/sh", &["-c", "echo hello; echo world >&2"]);
let expected = Some(CommandOutput {
stdout: String::from("hello\n"),
stderr: String::from("world\n"),
});

assert_eq!(result, expected)
}

#[test]
fn exec_with_non_zero_exit_code() {
let result = exec_cmd("false", &[]);
let expected = None;

assert_eq!(result, expected)
}
}

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