add shorthand for pattern matching

lib/index.js

@@ -19,7 +19,7 @@ module.exports = plugin;
  */
 
 function plugin(opts){
-  opts = opts || {};
+  opts = normalize(opts);
   var keys = Object.keys(opts);
   var match = matcher(opts);
 
@@ -79,6 +79,23 @@ function plugin(opts){
   };
 }
 
+/**
+ * Normalize an `options` dictionary.
+ *
+ * @param {Object} options
+ */
+
+function normalize(options){
+  options = options || {};
+
+  for (var key in options) {
+    var val = options[key];
+    if ('string' == typeof val) options[key] = { pattern: val };
+  }
+
+  return options;
+}
+
 /**
  * Generate a matching function for a given set of `collections`.
  *

test/index.js

@@ -30,6 +30,19 @@ describe('metalsmith-collections', function(){
       });
   });
 
+  it('should take a pattern shorthand string', function(done){
+    var metalsmith = Metalsmith('test/fixtures/basic');
+    metalsmith
+      .use(collections({
+        articles: '*.md'
+      }))
+      .build(function(err){
+        if (err) return done(err);
+        assert.equal(3, metalsmith.metadata().articles.length);
+        done();
+      });
+  });
+
   it('should accept a "sortBy" option', function(done){
     var metalsmith = Metalsmith('test/fixtures/sort');
     metalsmith