added no-empty-file rule (#14)

src/rules/no-empty-file.ts

@@ -0,0 +1,27 @@
+import { GherkinDocument } from '@cucumber/messages'
+
+import { LintError } from '../error'
+import { switchOrSeveritySchema } from '../schemas'
+import Rule from '../rule'
+
+/**
+ * Allowed:
+ * off | on | error | warn
+ */
+export const schema = switchOrSeveritySchema
+
+export const run = (rule: Rule, document: GherkinDocument): Array<LintError> => {
+  const errors: Array<LintError> = []
+
+  if (!document) {
+    errors.push({
+      message: 'Feature file is empty',
+      location: {
+        line: 0,
+        column: 0,
+      },
+    } as LintError)
+  }
+
+  return errors
+}

src/runner.ts

@@ -77,9 +77,6 @@ export default class Runner {
 
       const document = parser.parse(content.toString())
       const walk = walker.walkGherkinDocument(document)
-      if (!document || (document && !document.feature)) {
-        continue
-      }
 
       for (const rule of this.rules) {
         if (!rule.schema.enabled) {

tests/acceptance/features/no-empty-file/valid.feature

@@ -0,0 +1,18 @@
+Feature: No Empty File
+
+  Scenario: This is valid
+    Given I do something
+    When I do something else
+    Then I should have done something
+    And I should have done something else
+    But I shouldn't have done nothing
+
+  Scenario Outline: Valid Indentation
+    When I do each of these things
+      | <THING> |
+    Then I should have done something
+
+    Examples:
+      | THING |
+      | sleep |
+      | eat   |

tests/acceptance/no-empty-file.ts

@@ -0,0 +1,28 @@
+import path from 'node:path'
+import { Runner, Severity } from '../../src'
+import { expect } from 'chai'
+
+describe('No Empty File', () => {
+  it('returns errors if the rule fails', async () => {
+    const featureDirectory = path.join(import.meta.dirname, './features/no-empty-file')
+
+    const runner = new Runner({
+      configDirectory: '.',
+      featureDirectory,
+      rules: {
+        'no-empty-file': Severity.warn,
+      },
+    })
+
+    await runner.init()
+    const result = await runner.run()
+
+    expect(result.success).to.eq(false)
+    expect(result.errors.size).to.eq(1)
+    expect(result.errors.has(`${featureDirectory}/valid.feature`)).to.eq(false)
+
+    const errors = result.errors.get(`${featureDirectory}/invalid.feature`)
+    expect(errors.length).to.eq(1)
+    expect(errors[0].message).to.eq('Feature file is empty')
+  })
+})