Migrate from Steiger

Steiger is the linter of Feature-Sliced Design. Archangel’s fsd preset has a rule for each of Steiger’s 21 rules, with the same name and a link to Steiger’s page for it. A test in the archangel repository runs Steiger and the preset on the same repositories, and compares the files that each one reports.

Feature-Sliced Design tells you how to use the preset. This page tells you how to move from Steiger.

The config before

steiger.config.ts

import { defineConfig } from 'steiger';
import fsd from '@feature-sliced/steiger-plugin';

export default defineConfig([
  ...fsd.configs.recommended,
  {
    rules: {
      'fsd/insignificant-slice': 'off',
    },
  },
]);

The config after

archangel.config.ts

import { defineConfig, fsd } from '@enhance-eng/archangel';

export default defineConfig({
  extends: [fsd({ root: 'src' })],
  off: ['fsd/insignificant-slice'],
});

Steiger	archangel
...fsd.configs.recommended	extends: [fsd({ root: 'src' })]
All rules on	fsd({ root: 'src', strict: true })
'fsd/<rule>': 'off'	off: ['fsd/<rule>']
'fsd/<rule>': 'warn'	No equivalent. A rule is on or off.
ignores: [...]	ignore: [...] in the config, in .gitignore syntax. It removes the files from the whole check.
files: [...] with a rule off	Write a rule with the same name as the preset rule. Your rule replaces it.
A second FSD root	A second fsd({ root, name }) with its own name, for example fsd-admin.

Run it

1. Check the repository:

   Terminal

   $ npx archangel check
   error[may-not-import]: src/features/login/ui/login-form.ts may not import "../../signup", because files in "features" may not import "all of (fsd/features, not src/features/*/@x/**)" in a different instance
    --> src/features/login/ui/login-form.ts:1:28
     |
   1 | import { signupLink } from '../../signup';
     |                            ^^^^^^^^^^^^^^ remove the import, or move the code to files that may import it
     |
     = note: rule: fsd/forbidden-imports
     = note: reason: A module may import only from layers below its own, and a slice not from another slice of its layer, except through @x.
     = note: see: https://feature-sliced.github.io/steiger/rules/forbidden-imports
   
   checked 8 files and 8 imports: 1 problem
     fsd/shared matches nothing in this repository
     fsd/entities matches nothing in this repository
     fsd/widgets matches nothing in this repository
     fsd/processes matches nothing in this repository
   For what a code means, run `archangel docs may-not-import`.

   The feature login imports the feature signup, so fsd/forbidden-imports refuses it. The lines that say “matches nothing” are parts of the preset with no files. A repository usually has only some layers, so these lines are not errors.

2. Run npx archangel test. It checks the examples of each preset rule in your repository, under the preset’s root, with your tsconfig.

3. Remove Steiger when the results are the same.

The rules

Each rule name has the prefix of the preset, fsd/ by default. The rules that Steiger recommends are on by default. strict: true adds the four rules that Steiger has as options.

Steiger rule	archangel rule	On
fsd/forbidden-imports	fsd/forbidden-imports	Default
fsd/no-public-api-sidestep	fsd/no-public-api-sidestep	Default
fsd/public-api	fsd/public-api	Default
fsd/no-layer-public-api	fsd/no-layer-public-api	Default
fsd/no-reserved-folder-names	fsd/no-reserved-folder-names	Default
fsd/no-segmentless-slices	fsd/no-segmentless-slices	Default
fsd/no-segments-on-sliced-layers	fsd/no-segments-on-sliced-layers	Default
fsd/no-ui-in-app	fsd/no-ui-in-app	Default
fsd/segments-by-purpose	fsd/segments-by-purpose	Default
fsd/no-processes	fsd/no-processes	Default
fsd/typo-in-layer-name	fsd/typo-in-layer-name	Default
fsd/ambiguous-slice-names	fsd/ambiguous-slice-names	Default
fsd/inconsistent-naming	fsd/inconsistent-naming	Default
fsd/insignificant-slice	fsd/insignificant-slice	Default
fsd/repetitive-naming	fsd/repetitive-naming	Default
fsd/excessive-slicing	fsd/excessive-slicing	Default
fsd/shared-lib-grouping	fsd/shared-lib-grouping	Default
fsd/no-higher-level-imports	fsd/no-higher-level-imports	strict: true
fsd/no-cross-imports	fsd/no-cross-imports	strict: true
fsd/import-locality	fsd/import-locality	strict: true
fsd/no-wildcard-exports	fsd/no-wildcard-exports	strict: true

The rules about imports and folders are built-in conditions of archangel. The seven rules about names and counts, from typo-in-layer-name to shared-lib-grouping, are conditions of the preset’s plugin, and they read the whole tree as Steiger does.

Results that change

These differences are on purpose. The test that compares the two tools names each one.

• A slice is any folder in a sliced layer. The built-in rules take each folder directly in Entities, Features, Widgets or Pages as a slice, with or without segments. They do not know slice groups. Steiger finds a slice by the segments inside it. The plugin rules find slices and slice groups as Steiger does.
• Each folder in shared/ui and shared/lib needs an index file. fsd/public-api asks for it even when the segment has an index file of its own. Steiger checks those folders only when the segment has none.
• A misspelt layer is reported beside the real one. fsd/typo-in-layer-name reports src/featurez even when src/features exists. Steiger then reports nothing.
• A layer has its exact name. The built-in rules take only a folder named exactly as a layer. Steiger also reads 1_shared or _app as a layer.
• Code outside the layers is checked too. fsd/no-public-api-sidestep checks imports from files outside the layers, such as tests. A deep import from a test is still a sidestep. Steiger reads only the files in the layers.
• A re-export is an import. Each rule counts export ... from as an import, because a re-export loads the module.

One tool for more rules

Steiger checks Feature-Sliced Design only. With archangel, you can add your own tables and rules next to the preset, in the same config, and check them in one run.