fix(windows): use execFile for executing git

Fix problems with variable expansion and escaping by passing
arguments straight to git with execFile instead of going through
a shell to execute it.

Closes #11

index.js

@@ -1,6 +1,6 @@
 'use strict';
 var dargs = require('dargs');
-var exec = require('child_process').exec;
+var execFile = require('child_process').execFile;
 var split = require('split2');
 var stream = require('stream');
 var template = require('lodash.template');
@@ -15,29 +15,28 @@ function gitRawCommits(options) {
   options.from = options.from || '';
   options.to = options.to || 'HEAD';
 
+  var gitFormat = template('--format=<%= format %>%n' +
+    '------------------------ >8 ------------------------'
+  )(options);
+  var gitFromTo = template('<%- from ? [from, to].join("..") : to %>')(options);
+
   var args = dargs(options, {
     excludes: ['from', 'to', 'format']
   });
 
-  var cmd = template(
-    'git log --format="<%= format %>%n------------------------ >8 ------------------------" ' +
-    '"<%- from ? [from, to].join("..") : to %>" '
-  )(options) + args.join(' ');
-
-  if (process.platform === 'win32') {
-    // Git format strings have percent signs in them
-    // On windows percent signs need to be doubled to escape them,
-    // so that they aren't used for variable expansion
-    cmd.replace(/%/g, '%%');
-  }
+  args = [
+    'log',
+    gitFormat,
+    gitFromTo
+  ].concat(args);
 
   if (options.debug) {
-    options.debug('Your git-log command is:\n' + cmd);
+    options.debug('Your git-log command is:\ngit ' + args.join(' '));
   }
 
   var isError = false;
 
-  var child = exec(cmd, {
+  var child = execFile('git', args, {
     maxBuffer: Infinity
   });
 

test.js

@@ -132,8 +132,33 @@ it('should show your git-log command', function(done) {
   gitRawCommits({
     format: 'what%n%B',
     debug: function(cmd) {
-      expect(cmd).to.equal('Your git-log command is:\ngit log --format="what%n%B%n------------------------ >8 ------------------------" "HEAD" ');
+      expect(cmd).to.include('Your git-log command is:\ngit log --format');
       done();
     }
   });
 });
+
+it('should prevent variable expansion on windows', function(done) {
+  var i = 0;
+
+  gitRawCommits({
+    format: '%%cd%n%B'
+  })
+    .pipe(through(function(chunk, enc, cb) {
+      chunk = chunk.toString();
+
+      if (i === 0) {
+        expect(chunk).to.equal('%cd\nThird commit\n\n');
+      } else if (i === 1) {
+        expect(chunk).to.equal('%cd\nSecond commit\n\n');
+      } else {
+        expect(chunk).to.equal('%cd\nFirst commit\n\n');
+      }
+
+      i++;
+      cb();
+    }, function() {
+      expect(i).to.equal(3);
+      done();
+    }));
+});