Add the typo-in-layer-name rule (#102)

.changeset/unlucky-coins-accept.md

@@ -0,0 +1,6 @@
+---
+'@feature-sliced/steiger-plugin': minor
+'steiger': minor
+---
+
+Add typo-in-layer-name rule

README.md

@@ -74,6 +74,7 @@ Currently, Steiger is not extendable with more rules, though that will change in
   <tr> <td><a href="./packages/steiger-plugin-fsd/src/repetitive-naming/README.md"><code>repetitive-naming</code></a></td> <td>Ensure that all entities are named consistently in terms of pluralization.</td> </tr>
   <tr> <td><a href="./packages/steiger-plugin-fsd/src/segments-by-purpose/README.md"><code>segments-by-purpose</code></a></td> <td>Discourage the use of segment names that group code by its essence, and instead encourage grouping by purpose</td> </tr>
   <tr> <td><a href="./packages/steiger-plugin-fsd/src/shared-lib-grouping/README.md"><code>shared-lib-grouping</code></a></td> <td>Forbid having too many ungrouped modules in <code>shared/lib</code>.</td> </tr>
+  <tr> <td><a href="./packages/steiger-plugin-fsd/src/typo-in-layer-name/README.md"><code>typo-in-layer-name</code></a></td> <td>Ensure that all layers are named without any typos.</td> </tr>
   <tr> <td><a href="./packages/steiger-plugin-fsd/src/no-processes/README.md"><code>no-processes</code></a></td> <td>Discourage the use of the deprecated Processes layer.</td> </tr>
   <tr> <td><a href="./packages/steiger-plugin-fsd/src/import-locality/README.md"><code>import-locality</code></a></td> <td>Require that imports from the same slice be relative and imports from one slice to another be absolute.</td> </tr>
 </tbody>

packages/steiger-plugin-fsd/package.json

@@ -31,6 +31,7 @@
   ],
   "dependencies": {
     "@feature-sliced/filesystem": "^2.2.5",
+    "fastest-levenshtein": "^1.0.16",
     "lodash-es": "^4.17.21",
     "pluralize": "^8.0.0",
     "precinct": "^12.1.1",

packages/steiger-plugin-fsd/src/index.ts

@@ -15,6 +15,7 @@ import publicApi from './public-api/index.js'
 import repetitiveNaming from './repetitive-naming/index.js'
 import segmentsByPurpose from './segments-by-purpose/index.js'
 import sharedLibGrouping from './shared-lib-grouping/index.js'
+import typoInLayerName from './typo-in-layer-name/index.js'
 import noProcesses from './no-processes/index.js'
 import packageJson from '../package.json'
 
@@ -34,6 +35,7 @@ const allRules: Array<Rule> = [
   repetitiveNaming,
   segmentsByPurpose,
   sharedLibGrouping,
+  typoInLayerName,
   noProcesses,
 ]
 

packages/steiger-plugin-fsd/src/typo-in-layer-name/README.md

@@ -0,0 +1,29 @@
+# `typo-in-layer-name`
+
+Ensure that all layers are named consistently without any typos.
+
+Examples of project structures that pass this rule:
+
+```
+📂 shared
+📂 entities
+📂 features
+📂 widgets
+📂 pages
+📂 app
+```
+
+Examples of project structures that fail this rule:
+
+```
+📂 shraed  // ❌
+📂 entities
+📂 fietures  // ❌
+📂 wigdets  // ❌
+📂 page  // ❌
+📂 app
+```
+
+## Rationale
+
+The methodology contains a standardized set of layers. Enforcing these naming conventions is important for other developers, as well as for other rules of the linter to work correctly.

packages/steiger-plugin-fsd/src/typo-in-layer-name/index.spec.ts

@@ -0,0 +1,100 @@
+import { expect, it } from 'vitest'
+
+import typoInLayerName from './index.js'
+import { joinFromRoot, parseIntoFsdRoot } from '../_lib/prepare-test.js'
+
+it('reports no errors on a project without typos in layer names', () => {
+  const root = parseIntoFsdRoot(`
+    📂 shared
+    📂 entities
+    📂 features
+    📂 widgets
+    📂 pages
+    📂 app
+  `)
+
+  expect(typoInLayerName.check(root)).toEqual({ diagnostics: [] })
+})
+
+it('reports errors on a project with typos in layer names', () => {
+  const root = parseIntoFsdRoot(`
+    📂 shraed
+    📂 entities
+    📂 fietures
+    📂 wigdets
+    📂 page
+    📂 app
+  `)
+
+  const diagnostics = typoInLayerName.check(root).diagnostics
+  expect(diagnostics).toEqual([
+    {
+      message: 'Layer "page" potentially contains a typo. Did you mean "pages"?',
+      location: { path: joinFromRoot('page') },
+    },
+    {
+      message: 'Layer "shraed" potentially contains a typo. Did you mean "shared"?',
+      location: { path: joinFromRoot('shraed') },
+    },
+    {
+      message: 'Layer "fietures" potentially contains a typo. Did you mean "features"?',
+      location: { path: joinFromRoot('fietures') },
+    },
+    {
+      message: 'Layer "wigdets" potentially contains a typo. Did you mean "widgets"?',
+      location: { path: joinFromRoot('wigdets') },
+    },
+  ])
+})
+
+it('reports no errors on a project with custom layers if base layers are present', () => {
+  const root = parseIntoFsdRoot(`
+    📂 shared
+    📂 shapes
+    📂 entities
+    📂 entries
+    📂 features
+    📂 fixtures
+    📂 widgets
+    📂 pages
+    📂 places
+    📂 app
+    📂 amp
+  `)
+
+  expect(typoInLayerName.check(root)).toEqual({ diagnostics: [] })
+})
+
+it('reports errors on a project with custom layers if base layers are absent', () => {
+  const root = parseIntoFsdRoot(`
+    📂 shapes
+    📂 entries
+    📂 fixtures
+    📂 places
+    📂 amp
+  `)
+
+  const diagnostics = typoInLayerName.check(root).diagnostics
+  expect(diagnostics).toEqual([
+    {
+      message: 'Layer "amp" potentially contains a typo. Did you mean "app"?',
+      location: { path: joinFromRoot('amp') },
+    },
+    {
+      message: 'Layer "shapes" potentially contains a typo. Did you mean "shared"?',
+      location: { path: joinFromRoot('shapes') },
+    },
+    {
+      message: 'Layer "entries" potentially contains a typo. Did you mean "entities"?',
+      location: { path: joinFromRoot('entries') },
+    },
+    {
+      message: 'Layer "fixtures" potentially contains a typo. Did you mean "features"?',
+      location: { path: joinFromRoot('fixtures') },
+    },
+    {
+      message: 'Layer "places" potentially contains a typo. Did you mean "pages"?',
+      location: { path: joinFromRoot('places') },
+    },
+  ])
+})

packages/steiger-plugin-fsd/src/typo-in-layer-name/index.ts

@@ -0,0 +1,68 @@
+import type { Diagnostic, Rule } from '@steiger/types'
+import { NAMESPACE } from '../constants.js'
+import { LayerName, layerSequence } from '@feature-sliced/filesystem'
+import { distance } from 'fastest-levenshtein'
+import { basename } from 'node:path'
+import { joinFromRoot } from '../_lib/prepare-test.js'
+
+const LEVENSHTEIN_DISTANCE_UPPER_BOUND = 3
+
+const typoInLayerName = {
+  name: `${NAMESPACE}/typo-in-layer-name`,
+  check(root) {
+    const diagnostics: Array<Diagnostic> = []
+
+    // construct list of suggestions, like [{ input: 'shraed', suggestion: 'shared', distance: 2 }, ...],
+    // limit Levenshtein distance upper bound to 3,
+    // sort by Levenshtein distance in ascending order,
+    const suggestionsList = root.children
+      .filter((child) => child.type === 'folder')
+      .flatMap((child) => {
+        const layer = basename(child.path)
+
+        return layerSequence
+          .map((sequenceLayer) => ({
+            input: layer,
+            suggestion: sequenceLayer,
+            distance: distance(layer, sequenceLayer),
+          }))
+          .filter((layer) => layer.distance <= LEVENSHTEIN_DISTANCE_UPPER_BOUND)
+      })
+      .sort((a, b) => a.distance - b.distance)
+
+    const processedInputs: string[] = []
+    const suggestedLayers: LayerName[] = []
+
+    suggestionsList.forEach((layer) => {
+      // if Levenshtein distance is 0, the layer name is correct - add it as a "suggestion"
+      if (layer.distance === 0) {
+        suggestedLayers.push(layer.suggestion)
+
+        return
+      }
+
+      // if the input is already processed, the suggestion for this input is already added
+      if (processedInputs.includes(layer.input)) {
+        return
+      }
+
+      // if the suggestion is already added, it cannot be used for this input
+      if (suggestedLayers.includes(layer.suggestion)) {
+        return
+      }
+
+      // mark the input as processed & add suitable suggestion
+      processedInputs.push(layer.input)
+      suggestedLayers.push(layer.suggestion)
+
+      diagnostics.push({
+        message: `Layer "${layer.input}" potentially contains a typo. Did you mean "${layer.suggestion}"?`,
+        location: { path: joinFromRoot(layer.input) },
+      })
+    })
+
+    return { diagnostics }
+  },
+} satisfies Rule
+
+export default typoInLayerName

packages/steiger/README.md

@@ -74,6 +74,7 @@ Currently, Steiger is not extendable with more rules, though that will change in
   <tr> <td><a href="./packages/steiger-plugin-fsd/src/repetitive-naming/README.md"><code>repetitive-naming</code></a></td> <td>Ensure that all entities are named consistently in terms of pluralization.</td> </tr>
   <tr> <td><a href="./packages/steiger-plugin-fsd/src/segments-by-purpose/README.md"><code>segments-by-purpose</code></a></td> <td>Discourage the use of segment names that group code by its essence, and instead encourage grouping by purpose</td> </tr>
   <tr> <td><a href="./packages/steiger-plugin-fsd/src/shared-lib-grouping/README.md"><code>shared-lib-grouping</code></a></td> <td>Forbid having too many ungrouped modules in <code>shared/lib</code>.</td> </tr>
+  <tr> <td><a href="./packages/steiger-plugin-fsd/src/typo-in-layer-name/README.md"><code>typo-in-layer-name</code></a></td> <td>Ensure that all layers are named without any typos.</td> </tr>
   <tr> <td><a href="./packages/steiger-plugin-fsd/src/no-processes/README.md"><code>no-processes</code></a></td> <td>Discourage the use of the deprecated Processes layer.</td> </tr>
   <tr> <td><a href="./packages/steiger-plugin-fsd/src/import-locality/README.md"><code>import-locality</code></a></td> <td>Require that imports from the same slice be relative and imports from one slice to another be absolute.</td> </tr>
 </tbody>

packages/steiger/migrations/convert-config-to-flat.js

@@ -68,6 +68,7 @@ const ruleNames = [
   'repetitive-naming',
   'segments-by-purpose',
   'shared-lib-grouping',
+  'typo-in-layer-name',
   'no-processes',
   'import-locality',
 ]