added the possibility to use a function as message in git.commit (#181)

* added the possibility to use a function as message in git.commit

* remove unneccesary check

README.md

@@ -69,6 +69,15 @@ gulp.task('commit', function(){
     .pipe(git.commit('initial commit'));
 });
 
+// Run git commit with a computed commit message
+gulp.task('commit', function(){
+  let newVersion;
+  function computeNewVersion() { newVersion = /* ... */ }
+  return gulp.src('./git-test/*')
+    .pipe(computeNewVersion())
+    .pipe(git.commit(() => `Bumps to version ${newVersion}`));
+});
+
 // Run git commit with options
 gulp.task('commit', function(){
   return gulp.src('./git-test/*')

examples/gulpfile.js

@@ -25,6 +25,11 @@ gulp.task('commit', function() {
   .pipe(git.commit('initial commit'));
 });
 
+gulp.task('commitDelayed', function() {
+  gulp.src('./*')
+  .pipe(git.commit(function () { return 'commiting at exactly ' + new Date().toISOString(); }));
+});
+
 // Commit files with arguments
 gulp.task('commitopts', function() {
   gulp.src('./*')

lib/commit.js

@@ -11,7 +11,7 @@ var path = require('path');
 
 module.exports = function(message, opt) {
   if (!opt) opt = {};
-  if (!message || message.length === 0) {
+  if (!message) {
     if (opt.args.indexOf('--amend') === -1 && opt.disableMessageRequirement !== true) {
       throw new Error('gulp-git: Commit message is required git.commit("commit message") or --amend arg must be given');
     }
@@ -36,6 +36,10 @@ module.exports = function(message, opt) {
   var flush = function(cb) {
     var writeStdin = false;
     var cmd = 'git commit ';
+    // Allow delayed execution to determine the message
+    if (typeof message === 'function') {
+      message = message();
+    }
 
     if (message && opt.args.indexOf('--amend') === -1) {
 

test/commit.js

@@ -197,4 +197,22 @@ module.exports = function(git, util) {
         gitS.end();
       });
   });
+
+  it('should allow functions for git message', function(done) {
+    var fakeFile = util.testFiles[0];
+    var opt = {cwd: './test/repo/'};
+    var msg = 'bogus commit message';
+    var gitS = git.commit(function() { return msg; }, opt);
+    msg = 'initial commit';
+    gitS.once('finish', function() {
+      setTimeout(function() {
+        fs.readFileSync(util.testCommit)
+          .toString('utf8')
+          .should.match(/initial commit/);
+        done();
+      }, 100);
+    });
+    gitS.write(fakeFile);
+    gitS.end();
+  });
 };