refactor: always return an Array of results/errors from a plugin pi…

…peline

Always return an `Array` from a pipeline simplify the function utilization as it's more deterministic. Previously, it would return/throw a single value/error when called with a single input and an `Array` of results/errors when called with an `Array` of input.

index.js

@@ -1,4 +1,4 @@
-const {template, isPlainObject, castArray} = require('lodash');
+const {template, isPlainObject} = require('lodash');
 const marked = require('marked');
 const TerminalRenderer = require('marked-terminal');
 const envCi = require('env-ci');
@@ -81,7 +81,7 @@ async function run(options, plugins) {
   const commits = await getCommits(lastRelease.gitHead, options.branch, logger);
 
   logger.log('Call plugin %s', 'analyze-commits');
-  const type = await plugins.analyzeCommits({
+  const [type] = await plugins.analyzeCommits({
     options,
     logger,
     lastRelease,
@@ -101,14 +101,14 @@ async function run(options, plugins) {
 
   if (options.dryRun) {
     logger.log('Call plugin %s', 'generate-notes');
-    const notes = await plugins.generateNotes(generateNotesParam);
+    const [notes] = await plugins.generateNotes(generateNotesParam);
     logger.log('Release note for version %s:\n', nextRelease.version);
     if (notes) {
       process.stdout.write(`${marked(notes)}\n`);
     }
   } else {
     logger.log('Call plugin %s', 'generateNotes');
-    nextRelease.notes = await plugins.generateNotes(generateNotesParam);
+    [nextRelease.notes] = await plugins.generateNotes(generateNotesParam);
 
     logger.log('Call plugin %s', 'prepare');
     await plugins.prepare(
@@ -121,7 +121,7 @@ async function run(options, plugins) {
             nextRelease.gitHead = newGitHead;
             // Regenerate the release notes
             logger.log('Call plugin %s', 'generateNotes');
-            nextRelease.notes = await plugins.generateNotes(generateNotesParam);
+            [nextRelease.notes] = await plugins.generateNotes(generateNotesParam);
           }
           // Call the next publish plugin with the updated `nextRelease`
           return {options, logger, lastRelease, commits, nextRelease};
@@ -141,10 +141,7 @@ async function run(options, plugins) {
       {transform: (release, step) => ({...(isPlainObject(release) ? release : {}), ...nextRelease, ...step})}
     );
 
-    await plugins.success(
-      {options, logger, lastRelease, commits, nextRelease, releases: castArray(releases)},
-      {settleAll: true}
-    );
+    await plugins.success({options, logger, lastRelease, commits, nextRelease, releases}, {settleAll: true});
 
     logger.log('Published release: %s', nextRelease.version);
   }

lib/plugins/pipeline.js

@@ -49,7 +49,7 @@ module.exports = steps => async (input, {settleAll = false, getNextInput = ident
     input
   );
   if (errors.length > 0) {
-    throw errors.length === 1 ? errors[0] : new AggregateError(errors);
+    throw new AggregateError(errors);
   }
-  return results.length <= 1 ? results[0] : results;
+  return results;
 };

test/plugins/pipeline.test.js

@@ -18,24 +18,6 @@ test('Execute each function in series passing the same input', async t => {
   t.true(step2.calledBefore(step3));
 });
 
-test('With one step, returns the step values rather than an Array ', async t => {
-  const step1 = stub().resolves(1);
-
-  const result = await pipeline([step1])(0);
-
-  t.deepEqual(result, 1);
-  t.true(step1.calledWith(0));
-});
-
-test('With one step, throws the error rather than an AggregateError ', async t => {
-  const error = new Error('test error 1');
-  const step1 = stub().rejects(error);
-
-  const thrown = await t.throws(pipeline([step1])(0));
-
-  t.is(error, thrown);
-});
-
 test('Execute each function in series passing a transformed input from "getNextInput"', async t => {
   const step1 = stub().resolves(1);
   const step2 = stub().resolves(2);
@@ -96,7 +78,7 @@ test('Execute each function in series calling "transform" to modify the results
   t.deepEqual(getNextInput.args, [[5, 1 + 1], [5, 2 + 1], [5, 3 + 1], [5, 4 + 1]]);
 });
 
-test('Stop execution and throw error is a step rejects', async t => {
+test('Stop execution and throw error if a step rejects', async t => {
   const step1 = stub().resolves(1);
   const step2 = stub().rejects(new Error('test error'));
   const step3 = stub().resolves(3);

test/plugins/plugins.test.js

@@ -143,7 +143,7 @@ test('Merge global options with plugin options', async t => {
     t.context.logger
   );
 
-  const result = await plugins.verifyRelease();
+  const [result] = await plugins.verifyRelease();
 
   t.deepEqual(result.pluginConfig, {localOpt: 'local', globalOpt: 'global', otherOpt: 'locally-defined'});
 });