[New] order: add caseInsensitive: 'invert' option

Author: forivall

docs/rules/order.md

@@ -211,12 +211,12 @@ import index from './';
 import sibling from './foo';
 ```
 
-### `alphabetize: {order: asc|desc|ignore, caseInsensitive: true|false}`:
+### `alphabetize: {order: asc|desc|ignore, caseInsensitive: true|false|'invert'}`:
 
 Sort the order within each group in alphabetical manner based on **import path**:
 
 - `order`: use `asc` to sort in ascending order, and `desc` to sort in descending order (default: `ignore`).
-- `caseInsensitive`: use `true` to ignore case, and `false` to consider case (default: `false`).
+- `caseInsensitive`: use `true` to ignore case, `false` to consider case, and `'invert'` to sort lowercase before uppercase (default: `false`).
 
 Example setting:
 ```js

src/rules/order.js

@@ -265,6 +265,15 @@ function getSorter(ascending) {
   }
 }
 
+function swapCase(input) {
+  let result = ''
+  for (let i = 0; i < input.length; i++) {
+    const lower = input[i].toLowerCase()
+    result += input[i] === lower ? input[i].toUpperCase() : lower
+  }
+  return result
+}
+
 function mutateRanksToAlphabetize(imported, alphabetizeOptions) {
   const groupedByRanks = imported.reduce(function(acc, importedItem) {
     if (!Array.isArray(acc[importedItem.rank])) {
@@ -277,7 +286,10 @@ function mutateRanksToAlphabetize(imported, alphabetizeOptions) {
   const groupRanks = Object.keys(groupedByRanks)
 
   const sorterFn = getSorter(alphabetizeOptions.order === 'asc')
-  const comparator = alphabetizeOptions.caseInsensitive ? (a, b) => sorterFn(String(a).toLowerCase(), String(b).toLowerCase()) : (a, b) => sorterFn(a, b)
+  const comparator =
+    alphabetizeOptions.caseInsensitive === 'invert' ? (a, b) => sorterFn(swapCase(String(a)), swapCase(String(b)))
+    : alphabetizeOptions.caseInsensitive ? (a, b) => sorterFn(String(a).toLowerCase(), String(b).toLowerCase())
+    : (a, b) => sorterFn(a, b)
   // sort imports locally within their group
   groupRanks.forEach(function(groupRank) {
     groupedByRanks[groupRank].sort(comparator)
@@ -544,8 +556,10 @@ module.exports = {
             type: 'object',
             properties: {
               caseInsensitive: {
-                type: 'boolean',
-                default: false,
+                anyOf: [
+                  { type: 'boolean', default: false },
+                  { type: 'string', enum: ['invert'] },
+                ],
               },
               order: {
                 enum: ['ignore', 'asc', 'desc'],

tests/src/rules/order.js

@@ -2039,6 +2039,54 @@ ruleTester.run('order', rule, {
         message: '`foo` import should occur before import of `Bar`',
       }],
     }),
+    // Option alphabetize {order: 'asc': caseInsensitive: 'invert'}
+    test({
+      code: `
+        import a from 'bar';
+        import b from 'Foo';
+        import c from 'foo';
+
+        import index from './';
+      `,
+      output: `
+        import a from 'bar';
+        import c from 'foo';
+        import b from 'Foo';
+
+        import index from './';
+      `,
+      options: [{
+        groups: ['external', 'index'],
+        alphabetize: {order: 'asc', caseInsensitive: 'invert'},
+      }],
+      errors: [{
+        message: '`foo` import should occur before import of `Foo`',
+      }],
+    }),
+    // Option alphabetize {order: 'desc': caseInsensitive: 'invert'}
+    test({
+      code: `
+        import a from 'foo';
+        import b from 'Foo';
+        import c from 'bar';
+
+        import index from './';
+      `,
+      output: `
+        import b from 'Foo';
+        import a from 'foo';
+        import c from 'bar';
+
+        import index from './';
+      `,
+      options: [{
+        groups: ['external', 'index'],
+        alphabetize: {order: 'desc', caseInsensitive: 'invert'},
+      }],
+      errors: [{
+        message: '`Foo` import should occur before import of `foo`',
+      }],
+    }),
     // Alphabetize with parent paths
     test({
       code: `