feat(kernel): add support for command suggestions

packages/ace/package.json

@@ -32,6 +32,7 @@
   },
   "license": "MIT",
   "dependencies": {
+    "fast-levenshtein": "^2.0.6",
     "getopts": "^2.2.4",
     "kleur": "^3.0.3",
     "pad-right": "^0.2.2"

packages/ace/src/Kernel/index.ts

@@ -43,6 +43,14 @@ export class Kernel {
     return this
   }
 
+  /**
+   * Returns an array of command names suggestions for a given name.
+   */
+  public getSuggestions (name: string, distance = 3): string[] {
+    const levenshtein = require('fast-levenshtein')
+    return Object.keys(this.commands).filter((commandName) => levenshtein.get(name, commandName) <= distance)
+  }
+
   /**
    * Register a global flag to be set on any command. The flag callback is
    * executed before executing the registered command.

packages/ace/test/kernel.spec.ts

@@ -32,9 +32,19 @@ test.group('Kernel | register', () => {
     assert.throw(fn, 'Required argument {age} cannot come after optional argument {name}')
   })
 
-  test('return null when unable to find command', (assert) => {
+  test('return command suggestions for a given string', (assert) => {
     const kernel = new Kernel()
-    assert.isNull(kernel.find(['greet']))
+
+    class Install extends BaseCommand {
+      public static commandName = 'install'
+    }
+
+    class Greet extends BaseCommand {
+      public static commandName = 'greet'
+    }
+
+    kernel.register([Install, Greet])
+    assert.deepEqual(kernel.getSuggestions('itall'), ['install'])
   })
 })