feat(exists): expose the ability to check if config exists

Author: travi

src/existence-checker.js

@@ -0,0 +1,13 @@
+import loadConfig from './loader.js';
+
+export default async function ({name}) {
+  try {
+    await loadConfig({name});
+
+    return true;
+  } catch (e) {
+    if ('ENOCONFIG' === e.code) return false;
+
+    throw e;
+  }
+}

src/existence-checker.test.js

@@ -0,0 +1,34 @@
+import {describe, it, expect, vi} from 'vitest';
+import {when} from 'jest-when';
+import any from '@travi/any';
+
+import loadConfig from './loader.js';
+import exists from './existence-checker.js';
+
+vi.mock('./loader.js');
+
+describe('existence-checker', () => {
+  const name = any.word();
+
+  it('should return `true` if a config file exists', async () => {
+    when(loadConfig).calledWith({name}).mockResolvedValue(any.simpleObject());
+
+    expect(await exists({name})).toBe(true);
+  });
+
+  it('should return `false` if no config exists', async () => {
+    const error = new Error();
+    error.code = 'ENOCONFIG';
+    when(loadConfig).calledWith({name}).mockRejectedValue(error);
+
+    expect(await exists({name})).toBe(false);
+  });
+
+  it('should throw an error if an unexpected error occurs', async () => {
+    const error = new Error();
+    error.code = any.word();
+    when(loadConfig).calledWith({name}).mockRejectedValue(error);
+
+    await expect(exists({name})).rejects.toThrow(error);
+  });
+});

src/index.js

@@ -1,2 +1,3 @@
 export {default as write} from './writer.js';
 export {default as load} from './loader.js';
+export {default as exists} from './existence-checker.js';

test/integration/features/exists.feature

@@ -0,0 +1,16 @@
+Feature: exists
+
+  Scenario: json config exists
+    Given a "json" config file exists
+    When checking for config existence
+    Then the config is reported to be found
+
+  Scenario: yaml config exists
+    Given a "yaml" config file exists
+    When checking for config existence
+    Then the config is reported to be found
+
+  Scenario: no config exists
+    Given no config exists
+    When checking for config existence
+    Then the config is reported to not be found

test/integration/features/step_definitions/config-file-steps.js

@@ -3,7 +3,7 @@ import {promises as fs} from 'fs';
 import {dump, load as loadYaml} from 'js-yaml';
 import {fileTypes} from '@form8ion/core';
 // eslint-disable-next-line import/no-extraneous-dependencies,import/no-unresolved
-import {load, write} from '@form8ion/config-file';
+import {load, write, exists} from '@form8ion/config-file';
 
 import {After, Before, Given, Then, When} from '@cucumber/cucumber';
 import stubbedFs from 'mock-fs';
@@ -87,6 +87,10 @@ When('the provided config is merged into the existing file', async function () {
   return 'pending';
 });
 
+When('checking for config existence', async function () {
+  this.configExists = await exists({name: this.configName});
+});
+
 Then('the config is defined in the file', async function () {
   const {desiredConfigFileFormat} = this;
   const fileContents = await fs.readFile(
@@ -113,3 +117,11 @@ Then('a missing-config error is thrown', async function () {
   assert.equal(message, 'No configuration found');
   assert.equal(code, 'ENOCONFIG');
 });
+
+Then('the config is reported to not be found', async function () {
+  assert.equal(this.configExists, false);
+});
+
+Then('the config is reported to be found', async function () {
+  assert.equal(this.configExists, true);
+});