title: Colcon
description: This assignment is to help you self-assess your comprehension on **building tools**. Read carefully each question. Once answered, you will receive feedback. Good luck!
questions:

 - type: "multiple-answer"
   points: 1
   question: "A ROS package contains at least (select all that apply):"
   items:
    - choice: CMakeLists.txt
      comment: Correct! It is for the CMake build system for building software package.
      correct: true
    - choice: package.xml
      comment: Correct! It contains information about the package, e.g., package name, description, version, authors, maintainers, websites and dependencies.
      correct: true
    - choice: setup.sh
      comment: There might be a script in a package called 'setup.sh' but that is not necessary for the package to be recognized.
      correct: false
    - choice: .bashrc
      comment: The file is a script running whenever the terminal is started interactively.
      correct: false

 - type: "matching"
   points: 1
   question: "Match the functionalities of each directory after running `colcon build` in, e.g., `~/ros_workspace/`"
   items_a:
    - build
    - install
    - log
    - src
   items_b:
    - directory, where intermediate built files are stored in a subfolder created for each package.
    - directory, where each package will be installed to.
    - directory, containing logging information about each colcon invocation.
    - directory containing the source of the packages.
   distractors:
    - directory, containing configuration files.
    - directory, containing data files.
    - directory, containing documentation.view files

 - type: "multiple-choice"
   points: 1
   question: "Let's assume that a package `turtlebot_gazebo` is in `~/ros_workspace/src/`, `colcon build` should be run in which directory?"
   items:
    - choice: ~/ros_workspace/
      comment: Correct! The build command is run at the parent of the directory where the packages are, as the single command is able to build multiple packages.
      correct: true
    - choice: ~/ros_workspace/src
      comment: src contains the packages and is not the place where to run the command.
      correct: false
    - choice: ~/
      comment: The home directory is two levels away from the directory containing the packages. The command should be run on a different directory.
      correct: false
    - choice: ~/ros_workspace/src/turtlebot_gazebo/
      comment: The purpose of the command is to run one time the command for all custom packages. The command should be run in a different directory.
      correct: false

 - type: "fill-single"
   points: 1
   question: "Assuming that the packages have been built with `colcon build`, within `~/ros_workspace`, which command should be run so that the new packages can be found within ROS? Please type the full command."
   answer: 
    - source ~/ros_workspace/install/setup.sh
    - source ~/ros_workspace/install/setup.bash
   feedback_p: Great job!
   feedback_n: Think about the script that should be executed to populate the environment variables.

 - type: "multiple-answer"
   points: 1
   question: "How to fix an error of missing package? (select all that apply)"
   items:
    - choice: use apt to search if the package is existing in the repo and install it.
      comment: Correct! This is the first preferred method.
      correct: true
    - choice: search on GitHub (or other servers hosting repositories) and build that package in the workspace
      comment: Correct! This can be the second step, after finding out that it is not in the main ROS repository.
      correct: true
    - choice: copy the missing package in /opt/ros/melodic/share/
      comment: The package does not need to be directly copied in that folder.
      correct: false
    - choice: the error cannot be solved
      comment: There are at least two steps before giving up.
      correct: false