Restore support of empty prefix option

This restores a previous behavior (of `level-js` < 3) that unknown to
us, was provided by the since-removed IDBWrapper.

Backport of #184.

index.js

@@ -23,7 +23,7 @@ function Level (location, opts) {
  }
 
  this.location = location
- this.prefix = opts.prefix || DEFAULT_PREFIX
+ this.prefix = opts.prefix == null ? DEFAULT_PREFIX : opts.prefix
  this.version = parseInt(opts.version || 1, 10)
 }
 

test/custom-test.js

@@ -47,6 +47,27 @@ module.exports = function (leveljs, test, testCommon) {
  })
  })
 
+ test('empty prefix', function (t) {
+ var db = testCommon.factory({ prefix: '' })
+
+ t.ok(db.location, 'instance has location property')
+ t.is(db.prefix, '', 'instance has prefix property')
+
+ db.open(function (err) {
+ t.notOk(err, 'no open error')
+
+ var idb = db.db
+ var databaseName = idb.name
+ var storeNames = idb.objectStoreNames
+
+ t.is(databaseName, db.location, 'database name is prefixed')
+ t.is(storeNames.length, 1, 'created 1 object store')
+ t.is(storeNames.item(0), db.location, 'object store name equals location')
+
+ db.close(t.end.bind(t))
+ })
+ })
+
  test('put Buffer value, get Buffer value', function (t) {
  var level = testCommon.factory()
  level.open(function (err) {

test/structured-clone-test.js

@@ -128,7 +128,9 @@ var types = [
 
 // Types that are not supported by the structured clone algorithm
 var illegalTypes = [
- { name: 'Error', value: new Error() },
+ // Latest Chrome does seem to support Error, so skip this test.
+ // { name: 'Error', value: new Error() },
+
  { name: 'Function', value: function () {} },
  { name: 'DOMNode', value: global.document }
 ]