How to properly declare optional dependencies both as extras and in dedicated groups in Poetry?

From Poetry documentation about the difference between groups and extras:

Dependency groups, other than the implicit main group, must only contain dependencies you need in your development process. Installing them is only possible by using Poetry. To declare a set of dependencies, which add additional functionality to the project during runtime, use extras instead. Extras can be installed by the end user using pip.

This perfectly makes sense and works fine most of the time. However, during development one usually wants to install all the extras dependencies in order to test all the functionalities of the package. However, extras are not installed by default contrary to groups. Moreover, the Poetry documentation states that:

The dependencies specified for each extra must already be defined as project dependencies.

Dependencies listed in dependency groups cannot be specified as extras.

Thus, because it is not possible to define extras in a Poetry project that are defined in dependency groups and because extras are not installed by default, this left 2 suboptimal options for the developer to get a nice developer experience:

• Installing the project with poetry install --all-extras. This has the downside that the developer ha to remember to pass this option during development, even when the dev dependency group is installed.
• Mirroring the extras dependencies in a corresponding dependency group. This has the downside to introduce a lot of boilerplate and possible errors since dependencies are listed multiple times.

For instance, the second case would look like:

[tool.poetry.dependencies]
python = "^3.8,<3.12"
numpy = "^1.22"
scipy = { version = "^1.8", optional = true }

[tool.poetry.group.dev.dependencies]
scipy = "^1.8"

[tool.poetry.extras]
plot = ["scipy"]

In this example there is an extra that requires the SciPy dependency. This dependency is declared as optional in the main dependency group, as recommended by Poetry. However, this dependency should additionally be declared in the dev dependency group in order to organize the development dependencies and have it installed automatically.

Is there a simpler approach to solve this problem that do not requires specifying multiple times the same dependency?

source https://stackoverflow.com/questions/77512072/how-to-properly-declare-optional-dependencies-both-as-extras-and-in-dedicated-gr