Mix.Shell.Process

Mix shell that uses the current process mailbox for communication.

This module provides a Mix shell implementation that uses the current process mailbox for communication instead of IO.

As an example, when Mix.shell().info("hello") is called, the following message will be sent to the calling process:

{:mix_shell, :info, ["hello"]}

This is mainly useful in tests, allowing us to assert if given messages were received or not instead of performing checks on some captured IO. Since we need to guarantee a clean slate between tests, there is also a flush/1 function responsible for flushing all :mix_shell related messages from the process inbox.

Examples

Mix.shell().info("hello")

receive do
  {:mix_shell, :info, [msg]} -> msg
end

# => "hello"

send(self(), {:mix_shell_input, :prompt, "Pretty cool"})
Mix.shell().prompt?("How cool was that?!")
# => "Pretty cool"

Function cmd/2

Executes the given command and forwards its messages to the current process.

Function error/1

Forwards the error to the current process.

Function flush/1

Flushes all :mix_shell and :mix_shell_input messages from the current process.

If a callback is given, it is invoked for each received message.

Examples

flush(&IO.inspect/1)

Function info/1

Forwards the message to the current process.

Function print_app/0

Prints the current application if it was not printed yet.

Function prompt/1

Forwards the message to the current process.

It also checks the inbox for an input message matching:

{:mix_shell_input, :prompt, value}

If one does not exist, it will abort since there was no shell process inputs given. value must be a string.

Examples

The following will answer with "Meg" to the prompt "What's your name?":

# The response is sent before calling prompt/1 so that prompt/1 can read it
send(self(), {:mix_shell_input, :prompt, "Meg"})
Mix.shell().prompt("What's your name?")

Function yes?/2

Forwards the message to the current process.

It also checks the inbox for an input message matching:

{:mix_shell_input, :yes?, value}

If one does not exist, it will abort since there was no shell process inputs given. value must be true or false.

Example

# Send the response to self() first so that yes?/2 will be able to read it
send(self(), {:mix_shell_input, :yes?, true})
Mix.shell().yes?("Are you sure you want to continue?")