add optional branch parameter to count function

README.md

@@ -48,9 +48,9 @@ return the result of `git rev-parse HEAD`; optional `filePath` parameter can be
 
 return the current branch; optional `filePath` parameter can be used to run the command against a repo outside the current working directory
 
-#### `git.count()` → <Number>
+#### `git.count([branch])` → <Number>
 
-return the count of commits across all branches; this method will fail if the `git` command is not found in `PATH`
+returns the count of commits across all branches; optional `branch` parameter can be used to limit the count to a specific branch; this method will fail if the `git` command is not found in `PATH`
 
 #### `git.date()` → <Date>
 

index.js

@@ -168,8 +168,8 @@ function date() {
   return new Date(_command('git', ['log', '--no-color', '-n', '1', '--pretty=format:"%ad"']));
 }
 
-function count() {
-  return parseInt(_command('git', ['rev-list', '--all', '--count']), 10);
+function count(branch) {
+  return parseInt(_command('git', ['rev-list', '--count', branch || '--all']), 10);
 }
 
 function log() {

tests/index.js

@@ -19,6 +19,10 @@ result = git.count();
 assert.notEqual(result, 0, 'count() returns a non-zero number');
 assert.equal(Math.abs(result), result, 'count() returns a positive number');
 
+result = git.count('HEAD');
+assert.notEqual(result, 0, 'count() returns a non-zero number');
+assert.equal(Math.abs(result), result, 'count() returns a positive number');
+
 result = git.date();
 assert.equal(result instanceof Date, true, 'date() returns a date');