# [Greenline] ICON4Py - consolidation of test setup

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- Shaped by: Magdalena
- Appetite (FTEs, weeks):
- Developers: <!-- Filled in at the betting table unless someone is specifically required here -->

## Problem
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With the growth of the functionality in `icon4py` also test configuration has become more sophisticated, but the patterns used have diverged between the pure stencil codes and the greenline functionality.

## Appetite
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Half a cycle should be enough to clean up most of it.

## Solution
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The goal of the project is to consolidate.

- re-use `--backend` in greenline/ `datatest` s
- use `--grid`: allow for icon_global (R02B04), icon_local grids (MCH_CH_R04B09).
- populate the `--grid=icon_grid` from the grid file instead of reading serialized data
- (optional) test hierarchy: create a more refined testing hierarchy in order to run tests more selectively and therewith speed up CI runs

## Rabbit holes
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It is not the goal of the project to refactor a lot of tests and for example bring them all to the `StencilTest` patterns, even if some of them could be converted.

## No-gos
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## Progress
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- [x] run with grid from gridfile

- [x] use `--grid`: allow for icon_global (R02B04), icon_local grids (MCH_CH_R04B09)

- [ ] re-use `--backend` in greenline/ `datatest` s
- [ ] extract global backend in greenline -> [PR](https://github.com/C2SM/icon4py/pull/412)
- [ ] set backend from option, add a warning if run with slow or untested backend
- [ ] update `readme` s where appropriate
- [ ] (optional) improve test hierarchy