Automated migration to groups during `poetry add --group dev`

Running poetry add --group dev (or poetry add --dev) with a dependency that already exists in the [tool.poetry.dev-dependencies] section adds a new entry in [tool.poetry.group.dev.dependencies that may conflict with the existing entry.

It’s easily fixed (updating [tool.poetry.dev-dependencies] to [tool.poetry.group.dev.dependencies], and merging the sections if the extra entry has already been added) but it makes the Poetry 1.1 -> 1.2 upgrade painful if you’ve got lots of repos.

# syntax=docker/dockerfile:1.3-labs
FROM python:3.8
RUN pip install poetry==1.2.1
WORKDIR /src
COPY <<"EOF" pyproject.toml
[tool.poetry]
name = ""
version = "0.1.0"
description = ""
authors = [""]

[tool.poetry.dependencies]
python = "^3.8"

[tool.poetry.dev-dependencies]
tomli = "1.0.0"

EOF

# Using `poetry add --group dev` and `poetry add --dev` produce the same result.
RUN poetry add --group dev tomli@2.0.0
RUN cat pyproject.toml && poetry lock

produces

 > [6/6] RUN cat pyproject.toml && poetry lock:
#14 0.534 [tool.poetry]
#14 0.534 name = ""
#14 0.534 version = "0.1.0"
#14 0.534 description = ""
#14 0.534 authors = [""]
#14 0.534
#14 0.534 [tool.poetry.dependencies]
#14 0.534 python = "^3.8"
#14 0.534
#14 0.534 [tool.poetry.dev-dependencies]
#14 0.534 tomli = "1.0.0"
#14 0.534
#14 0.534 [[tool.poetry.source]]
#14 0.534 name = 'simple'
#14 0.534 url = 'https://pypi.org/simple'
#14 0.534 default = true
#14 0.534
#14 0.534
#14 0.534 [tool.poetry.group.dev.dependencies]
#14 0.534 tomli = "2.0.0"
#14 0.534
#14 1.122 Updating dependencies
#14 1.123 Resolving dependencies...
#14 1.133
#14 1.133 Because  depends on both tomli (2.0.0) and tomli (1.0.0), version solving failed.

edit: Removed unnecessary [tool.poetry.source] section in Dockerfile.

[neersighted]

I assume that’s add -G dev? I think that’s up to us to decide – my immediate thoughts are we could do a wholesale migration the first time -G dev is used. That is to say, migrate everything from dev-dependencies to groups.dev, write pyproject.toml, and then do the add as normal.

Yes, this forces migration for users who are using -G dev on the command line, but we already effectively do that – this just removes the split brain situation.

[neersighted]

dev-dependencies is implicitly used/combined right now – I don’t think we can walk back from that behavior immediately – warning and removing it in a future version is better, I think.