feat: set tag author and committer name/email

Use [Git Environment Variables](https://git-scm.com/book/en/v2/Git-Internals-Environment-Variables#Committing). Set default values if environement variables are not set.

lib/definitions/constants.js

@@ -0,0 +1,9 @@
+const RELEASE_TYPE = ['major', 'premajor', 'minor', 'preminor', 'patch', 'prepatch', 'prerelease'];
+
+const FIRST_RELEASE = '1.0.0';
+
+const COMMIT_NAME = 'semantic-release-bot';
+
+const COMMIT_EMAIL = 'semantic-release-bot@martynus.net';
+
+module.exports = {RELEASE_TYPE, FIRST_RELEASE, COMMIT_NAME, COMMIT_EMAIL};

lib/definitions/errors.js

@@ -2,7 +2,7 @@ const url = require('url');
 const {inspect} = require('util');
 const {toLower, isString} = require('lodash');
 const pkg = require('../../package.json');
-const RELEASE_TYPE = require('./release-types');
+const {RELEASE_TYPE} = require('./constants');
 
 const homepage = url.format({...url.parse(pkg.homepage), ...{hash: null}});
 const stringify = obj => (isString(obj) ? obj : inspect(obj, {breakLength: Infinity, depth: 2, maxArrayLength: 5}));

lib/definitions/plugins.js

@@ -1,5 +1,5 @@
 const {isString, isFunction, isArray, isPlainObject} = require('lodash');
-const RELEASE_TYPE = require('./release-types');
+const {RELEASE_TYPE} = require('./constants');
 
 const validatePluginConfig = conf => isString(conf) || isString(conf.path) || isFunction(conf);
 

lib/definitions/release-types.js

@@ -1 +0,0 @@
-module.exports = ['major', 'premajor', 'minor', 'preminor', 'patch', 'prepatch', 'prerelease'];

lib/get-next-version.js

@@ -1,4 +1,5 @@
 const semver = require('semver');
+const {FIRST_RELEASE} = require('./definitions/constants');
 
 module.exports = (type, lastRelease, logger) => {
   let version;
@@ -6,7 +7,7 @@ module.exports = (type, lastRelease, logger) => {
     version = semver.inc(lastRelease.version, type);
     logger.log('The next release version is %s', version);
   } else {
-    version = '1.0.0';
+    version = FIRST_RELEASE;
     logger.log('There is no previous release, the next release version is %s', version);
   }