fix(release): more reliable branch detection

Fixes dry-run issue on detached head checkouts.

package.json

@@ -51,6 +51,7 @@
 		"cross-env": "^5.0.5",
 		"cross-spawn": "^6.0.4",
 		"doctoc": "^1.3.0",
+		"env-ci": "^2.1.1",
 		"eslint": "^4.7.2",
 		"eslint-config-tradeshift": "^5.0.0",
 		"eslint-plugin-jest": "^21.17.0",

src/__mocks__/env-ci.js

@@ -0,0 +1 @@
+module.exports = jest.fn();

src/scripts/__tests__/travis-after-success.js

@@ -11,28 +11,24 @@ cases(
 	({ version = '0.0.0-semantically-released', hasCoverageDir = true, branch = 'master' }) => {
 		// beforeEach
 		const { sync: crossSpawnSyncMock } = require('cross-spawn');
+		const envCiMock = require('env-ci');
+
 		const utils = require('../../utils');
 		utils.resolveBin = (modName, { executable = modName } = {}) => executable;
 		const originalExit = process.exit;
 		process.exit = jest.fn();
 
 		// tests
 		crossSpawnSyncMock.mockClear();
-		crossSpawnSyncMock.mockReturnValue({
-			stdout: {
-				toString() {
-					return branch;
-				}
-			}
-		});
+		envCiMock.mockReturnValue({ branch });
 		if (version) {
 			utils.pkg.version = version;
 		}
 		utils.hasFile = filename => filename === 'coverage' && hasCoverageDir;
 		require('../travis-after-success');
-		expect(crossSpawnSyncMock).toHaveBeenCalledTimes(2);
-		const [, secondCall] = crossSpawnSyncMock.mock.calls;
-		const [script, calledArgs] = secondCall;
+		expect(crossSpawnSyncMock).toHaveBeenCalledTimes(1);
+		const [firstCall] = crossSpawnSyncMock.mock.calls;
+		const [script, calledArgs] = firstCall;
 		expect([script, ...calledArgs].join(' ')).toMatchSnapshot();
 
 		// afterEach

src/scripts/travis-after-success.js

@@ -1,4 +1,4 @@
-
+const envCi = require('env-ci');
 const spawn = require('cross-spawn');
 const { resolveBin, getConcurrentlyArgs, hasFile, fromRoot, pkg } = require('../utils');
 
@@ -7,15 +7,10 @@ const autorelease = pkg.version === '0.0.0-semantically-released';
 // We don't care about the TravisCI validation
 const releaseConfig = hasFile('release.config.js') ? require(fromRoot('release.config.js')) : {};
 const releaseBranch = releaseConfig.branch || 'master';
-const currentBranch = spawn
-	.sync('git', ['rev-parse', '--abbrev-ref', 'HEAD'])
-	.stdout.toString()
-	.trim();
+const { branch } = envCi();
 // Run a dry-run release when not on master
-const dryRun = currentBranch !== releaseBranch;
-const releaseFlags = ['--no-ci', dryRun ? '--dry-run' : '']
-	.filter(Boolean)
-	.join(' ');
+const dryRun = branch !== releaseBranch;
+const releaseFlags = ['--no-ci', dryRun ? '--dry-run' : ''].filter(Boolean).join(' ');
 
 const result = spawn.sync(
 	resolveBin('concurrently'),
@@ -25,7 +20,9 @@ const result = spawn.sync(
 				? "echo installing codecov && npx -p codecov -c 'echo running codecov && codecov'"
 				: null,
 			release: autorelease
-				? `echo installing semantic-release && npx -p semantic-release@15 -c 'echo running semantic-release ${dryRun ? 'dry run' : ''} && semantic-release ${releaseFlags}'`
+				? `echo installing semantic-release && npx -p semantic-release@15 -c 'echo running semantic-release ${
+						dryRun ? 'dry run' : ''
+				  } && semantic-release ${releaseFlags}'`
 				: null
 		},
 		{ killOthers: false }