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    0.1.2 • Public • Published


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    CLI capture tool for testing command-line apps


    This tool allows you to simulate a separate command-line environment within the current process, automatically capturing any input/output for the simulated process. It works by temporarily faking process.argv and stdio (and optionally redirecting stdio), so your CLI app code has no idea it is actually being run in a test environment.

    process.exit() and uncaught errors are handled gracefully, returning the process exit code and the captured stdio contents.


    var mockCli = require('mock-cli');
    var assert = require('assert');
    var argv = ['node', 'hello-world-app.js', '--foo', 'bar']; // Fake argv
    var stdio = {
        stdin: require('./mocks/fakeInputStream'), // Hook up a fake input stream
        stdout: process.stdout, // Display the captured output in the main console
        stderr: process.stderr // Display the captured error output in the main console
    var kill = mockCli(argv, stdio, function onProcessComplete(error, result) {
        var exitCode = result.code; // Process exit code
        var stdout = result.stdout; // UTF-8 string contents of process.stdout
        var stderr = result.stderr; // UTF-8 string contents of process.stderr
        assert.equal(exitCode, 0);
        assert.equal(stdout, 'Hello, world!\n');
        assert.equal(stderr, '');
    // Execute the CLI task
    // Kill the task if still running after one second
    setTimeout(kill, 1000);


    mockCli(argv, stdio, exitCallback)

    Simulate a separate command-line environment within the current process


    Name Type Required Default Description
    argv Array No process.argv Fake argv for the simulated process
    stdio object No null Object containing streams that are used to fake stdio
    stdio.stdin Stream No null Input stream that is piped into the simulated process as process.stdin
    stdio.stdout Stream No null Output stream that is connected to process.stdout of the simulated process
    stdio.stderr Stream No null Error stream that is connected to process.stderr of the simulated process
    errorCallback function No null Callback that is invoked once the simulated process completes or throws an uncaught exception
    • errorCallback has the following signature:

      ##### function(error, result)

      ###### Arguments:

      Name Type Description
      error Error Uncaught exception thrown by the simulated process
      result object Object containing information about the simulated process
      result.code number Process exit code, or 1 on an uncaught exception
      result.stdin string UTF-8 contents of process.stdin, captured during simulation
      result.stdout string UTF-8 contents of process.stdout, captured during simulation
      result.stderr string UTF-8 contents of process.stderr, captured during simulation


    function Function that kills the simulated process (as if the user pressed Ctrl+C).

    • This function returns a results object, as seen in exitCallback arguments.


    npm i mock-cli

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