# How to install packages which are needed only for development

**URL:** <https://discourse.julialang.org/t/how-to-install-packages-which-are-needed-only-for-development/21815>\
**Category:** General Usage\
**Tags:** package-manager\
**Created:** [March 13, 2019, 12:22pm UTC](https://discourse.julialang.org/t/how-to-install-packages-which-are-needed-only-for-development/21815 "2019-03-13T12:22:13Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![ffevotte](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ffevotte/32/6587_2.png) [@ffevotte](https://discourse.julialang.org/u/ffevotte)\
**Post date:** [March 13, 2019, 12:22pm UTC](https://discourse.julialang.org/t/how-to-install-packages-which-are-needed-only-for-development/21815/1 "2019-03-13T12:22:13Z")

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I’m currently preparing a training session, and this process triggers again some questions that I had when initially discovering Julia and which haven’t really disappeared since then.

Here is the current situation: I’m preparing a training session in Julia, where trainees should ideally learn how to develop their own packages. This of course includes managing the dependencies of their own projects/packages (which is a fairly well-documented process). But this also includes using packages such as `Revise`, `BenchmarkTools`, `Profile`+`ProfileView`… which are not strict dependencies of anything; more like useful elements to incorporate in your workflow. I’d like to provide an easy way for all trainees to install these packages beforehand, so that ideally we will not depend too much on available Internet bandwidth on D day.

**Preliminary question:**

On my system, I installed all those packages in the default (v1.1) environment. Is that the correct way of doing things? It appears to me that, when a package is activated, you get access to:

1. the package itself
2. all packages that were `Pkg.add`ed in the environment of the package
3. all packages that were `Pkg.add`ed in the default environment

And `Pkg.test` checks that actually using the package (and running its test suite) makes use only of the first 2 categories above, as well as Test-specific dependencies added. By the way, it is not clear to me how these test-specific dependencies should be added: is it possible to avoid by-hand editing of `Project.toml`? Another thing which is not clear to me: in which environment does `Pkg.test` install test-specific dependencies if they were missing?

I haven’t found any place in the documentation (neither of [modules](https://docs.julialang.org/en/v1/manual/modules/) nor of [Pkg](https://julialang.github.io/Pkg.jl/)) where these details are clearly documented. I might very well have missed something; otherwise, I’d be glad to propose PRs to the appropriate documentations.

  

Back to my current problem: a first option would be to provide a `Project.toml` file that my trainees would put in their `~/.julia/environments/v1.1/` folder. But then, if some of the trainees have already installed some packages they rely on, my list will override theirs, potentially causing unpleasant surprises later.

Another option (currently my favorite) consists in providing a simple script which goes like this:

```julia
using Pkg

# ensure we are in the default (home) environment
Pkg.activate()

# Install dev tools
Pkg.add("Revise")
Pkg.add("BenchmarkTools")
#...

```

**Question 1:** Is the above a good way of doing things ?

  

**Question 2:** How can I test this? I.e make sure I did not forget any tools in my list. I currently:

1. move the whole `~/.julia` directory away;
2. try and install everything in an empty environment, then check that I can perform everything asked in the training session;
3. move my original `~/.julia` back.

Is there a better way of doing this?

  

PS: Sorry for the long question, and thanks to anyone taking the time and effort to read until here…

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**Author:** ![fredrikekre](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/fredrikekre/32/1688_2.png) [@fredrikekre](https://discourse.julialang.org/u/fredrikekre)\
**Post date:** [March 13, 2019, 12:49pm UTC](https://discourse.julialang.org/t/how-to-install-packages-which-are-needed-only-for-development/21815/2 "2019-03-13T12:49:38Z")

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> [@ffevotte](#):
>
> On my system, I installed all those packages in the default (v1.1) environment. Is that the correct way of doing things?

It’s one way, I usually use that myself

> [@ffevotte](#):
>
> It appears to me that, when a package is activated, you get access to:

Yea, well, if those are in the `LOAD_PATH` (see below).

> [@ffevotte](#):
>
> is it possible to avoid by-hand editing of `Project.toml` ?

No.

> [@ffevotte](#):
>
> nother thing which is not clear to me: in which environment does `Pkg.test` install test-specific dependencies if they were missing?

It’s a temporary environment that is cleaned up when tests are done.

> [@ffevotte](#):
>
> I haven’t found any place in the documentation (neither of [modules](https://docs.julialang.org/en/v1/manual/modules/) nor of [Pkg](https://julialang.github.io/Pkg.jl/)) where these details are clearly documented.

Stacking of LOAD\_PATH is documenter here: [Environment Variables · The Julia Language](https://docs.julialang.org/en/v1.2-dev/manual/environment-variables/#JULIA_LOAD_PATH-1).

> [@ffevotte](#):
>
> **Question 1:** Is the above a good way of doing things ?

Sure, seems easiest.

> [@ffevotte](#):
>
> **Question 2:** How can I test this? I.e make sure I did not forget any tools in my list. I currently:
> 
> 1. move the whole `~/.julia` directory away;
> 2. try and install everything in an empty environment, then check that I can perform everything asked in the training session;
> 3. move my original `~/.julia` back.
> 
> Is there a better way of doing this?

Instead of moving things you can set `DEPOT_PATH` to some test-directory, e.g. by setting `JULIA_DEPOT_PATH`, see [Environment Variables · The Julia Language](https://docs.julialang.org/en/v1.2-dev/manual/environment-variables/#JULIA_DEPOT_PATH-1)

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<div class="post-metadata">

**Author:** ![ffevotte](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/ffevotte/32/6587_2.png) [@ffevotte](https://discourse.julialang.org/u/ffevotte)\
**Post date:** [March 13, 2019, 3:33pm UTC](https://discourse.julialang.org/t/how-to-install-packages-which-are-needed-only-for-development/21815/3 "2019-03-13T15:33:33Z")

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Thank you for the detailed answer!

To recap, IIUC, `Pkg.Test` runs tests in a context where `LOAD_PATH` is something like: `["@", "@stdlib"]`. I now understand that the current behavior can be explained by piecing together information coming from various places in the documentation. Wouldn’t there be room for a small summarized explanation in [module file paths](https://docs.julialang.org/en/v1/manual/modules/#Module-file-paths-1), which would link to other places such as [`LOAD_PATH`](https://docs.julialang.org/en/v1.2-dev/base/constants/#Base.LOAD_PATH) (it already does) or [`Pkg`](https://docs.julialang.org/en/v1/stdlib/Pkg/)? Most importantly, such a paragraph would tell users what to do when a module they want to use/import is not found, depending on the situation:

- is it the top-level module of their current project? \rightarrow `Pkg.activate` the project
- is it third-party code that their current project depends on? \rightarrow `Pkg.add` in the current package
- is it something that they rely on for their workflow? \rightarrow `Pkg.add` in the home environment
- something else (what?) \rightarrow `push!` to `LOAD_PATH`

I’m under the impression that the whole system has been carefully devised in such a way that users almost never have to fiddle with `LOAD_PATH`, yet this is the first (only?) thing that is mentioned in the [modules](https://docs.julialang.org/en/v1/manual/modules) section of the manual…

As I said, if I understood things correctly (please correct me!) and if there is some agreement to this proposal for a bit more documentation on these matters, I’m willing to prepare a PR.

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**Author:** ![kristoffer.carlsson](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/kristoffer.carlsson/32/22_2.png) [@kristoffer.carlsson](https://discourse.julialang.org/u/kristoffer.carlsson)\
**Post date:** [March 13, 2019, 3:36pm UTC](https://discourse.julialang.org/t/how-to-install-packages-which-are-needed-only-for-development/21815/4 "2019-03-13T15:36:49Z")

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> [@ffevotte](#):
>
> I’m under the impression that the whole system has been carefully devised in such a way that users almost never have to fiddle with `LOAD_PATH` , yet this is the first (only?) thing that is mentioned in the [modules](https://docs.julialang.org/en/v1/manual/modules) section of the manual…

These docs were written when modifying `LOAD_PATH` was the standard way of making packages visible to Julia, but with the new package manager this has changed so the docs are indeed a bit “old”.