How to develop a new feature in the template?

[pQraus]

Hi
Actually, we are very happy with the options which copier provide us for templating. But I have question and maybe it is a bug.

How to add new features / fix bugs in the template repository? Do you have a workflow for this?

Let's say you want to add a new feature in your template. Because the config in the template repo is only a template you can't really test the scripts ... You will need an actual project to do this.

Let me explain our current workflow:

• This is our template:

  template_repo
  ├── config.conf.jinja
  ├── {{ _copier_conf.answers_file }}.jinja
  ├── copier.yaml
  └── main.py
  

  The python script (main.py) read the rendered config file:

  with open("config.conf", "r") as file:
    config = file.read()
    print(config)

1. Create a project from this template (copier template_repo .)
2. Now we want to add a feature in our main.py (because the python script uses the config file it can be only executed/tested in the project). After this our python script looks like this:

with open("config.conf", "r") as file:
  config = file.read()
  print(config)
print("Script finished")

3. We commit the changes in the project repository.
4. To apply the changes to the template we create a Git-patch: git format-patch master..feature-branch (in project repo)
5. Apply the patch into the template repo: git am path/to/patch/file(s)
   Now the new feature is in our template.
6. We want to synchronize our project with the template repository (it is also a check if we have applied the changes correctly). Therefore we run copier update in the project repo.
7. When everything is fine only the .copier-answers.yml should be changed. But actually there is also a .rej file. For the explained example it is the main.py.rej:

diff a/main.py b/main.py	(rejected hunks)
@@ -2,2 +2,3 @@ with open("config.conf", "r") as file:
   config = file.read()
-    print(config)
\ No newline at end of file
+    print(config)
+print("Script finished")
\ No newline at end of file

Why does this file exist? What is the purpose? Does it is a bug? We expect that there is only the change in the answers-file because the main.py in this project is already updated.

8. (Merge the feature branch into main (in project))

Is there another workflow?
How can we disable the creation of the .rej file?

[yajo]

El mar., 19 jul. 2022 9:13, pQraus ***@***.***> escribió:

How to add new features / fix bugs in the template repository? Do you have a workflow for this? Let's say you want to add a new feature in your template. Because the config in the template repo is only a template you can't really test the scripts ... You will need an actual project to do this.

All you have to do is to add unit tests to your template. In those tests, render the project to a temporary directory and make your assertions. Check out this project where I was a maintainer some time ago. In the tests folder, you can see it uses pytest to test all relevant template features: https://github.com/Tecnativa/doodba-copier-template/tree/a73f1109277659121502d740c9039c09d1e7a9aa/tests This way, you can do TDD in the template directly.

- When everything is fine only the .copier-answers.yml should be changed. But actually there is also a .rej file. For the explained example it is the main.py.rej: diff a/main.py b/main.py (rejected hunks) @@ -2,2 +2,3 @@ with open("config.conf", "r") as file: config = file.read() - print(config) \ No newline at end of file + print(config) +print("Script finished") \ No newline at end of file Why does this file exist? What is the purpose? Does it is a bug? We expect that there is only the change in the answers-file because the main.py in this project is already updated.

That file is created by copier when it finds a conflict that it cannot solve automatically during an update. Check out the docs: https://copier.readthedocs.io/en/stable/updating/ In your case, it might be related to those files with `No newline at end of file`. When you add one line to a file like that, you're in reality changing 2 lines: the 1st one gets changed with a newline at the end, and the 2nd one is added. This produces more diff than you expect, and it's sometimes the source of unexpected conflicts. This is a classic problem. Advanced code editors allow to configure automatic addition of newline at the end always. That way, adding a line at the bottom actually produces a diff of 1 line.

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[pQraus]

Thanks 👍