[New] no-cycle: allow maxDepth option to be "∞"

CHANGELOG.md

@@ -7,6 +7,7 @@ This change log adheres to standards from [Keep a CHANGELOG](http://keepachangel
 ## [Unreleased]
 ### Added
 - [`no-unused-modules`]: consider exported TypeScript interfaces, types and enums ([#1819], thanks [@nicolashenry])
+- [`no-cycle`]: allow `maxDepth` option to be `"∞"` (thanks [@ljharb])
 
 ### Fixed
 - [`order`]/TypeScript: properly support `import = object` expressions ([#1823], thanks [@manuth])

docs/rules/no-cycle.md

@@ -2,7 +2,7 @@
 
 Ensures that there is no resolvable path back to this module via its dependencies.
 
-This includes cycles of depth 1 (imported module imports me) to `Infinity`, if the
+This includes cycles of depth 1 (imported module imports me) to `"∞"` (or `Infinity`), if the
 [`maxDepth`](#maxdepth) option is not set.
 
 ```js

src/rules/no-cycle.js

@@ -14,10 +14,18 @@ module.exports = {
     type: 'suggestion',
     docs: { url: docsUrl('no-cycle') },
     schema: [makeOptionsSchema({
-      maxDepth:{
-        description: 'maximum dependency depth to traverse',
-        type: 'integer',
-        minimum: 1,
+      maxDepth: {
+        oneOf: [
+          {
+            description: 'maximum dependency depth to traverse',
+            type: 'integer',
+            minimum: 1,
+          },
+          {
+            enum: ['∞'],
+            type: 'string',
+          },
+        ],
       },
       ignoreExternal: {
         description: 'ignore external modules',
@@ -32,7 +40,7 @@ module.exports = {
     if (myPath === '<text>') return {} // can't cycle-check a non-file
 
     const options = context.options[0] || {}
-    const maxDepth = options.maxDepth || Infinity
+    const maxDepth = typeof options.maxDepth === 'number' ? options.maxDepth : Infinity
     const ignoreModule = (name) => options.ignoreExternal ? isExternalModule(name) : false
 
     function checkSourceValue(sourceNode, importer) {

tests/src/rules/no-cycle.js

@@ -161,6 +161,16 @@ ruleTester.run('no-cycle', rule, {
       parser: require.resolve('babel-eslint'),
       errors: [error(`Dependency cycle via ./flow-types-depth-two:4=>./depth-one:1`)],
     }),
+    test({
+      code: 'import { foo } from "./depth-two"',
+      options: [{ maxDepth: Infinity }],
+      errors: [error(`Dependency cycle via ./depth-one:1`)],
+    }),
+    test({
+      code: 'import { foo } from "./depth-two"',
+      options: [{ maxDepth: '∞' }],
+      errors: [error(`Dependency cycle via ./depth-one:1`)],
+    }),
   ],
 })
 // })