Use promise API of db.open() and close() in tests

test/index.js

@@ -4,7 +4,7 @@ const shape = require('./shape')
 const cloneable = require('./cloneable')
 
 module.exports = function suite (test, testCommon) {
-  test('db has manifest', function (t) {
+  test('db has manifest', async function (t) {
     const db = testCommon.factory()
     const manifest = db.supports
 
@@ -15,15 +15,10 @@ module.exports = function suite (test, testCommon) {
       additionalMethods: Object.assign({}, manifest.additionalMethods)
     })
 
-    db.open(function (err) {
-      t.ifError(err, 'no open error')
-      t.same(db.supports, before, 'manifest did not change after open')
+    await db.open()
+    t.same(db.supports, before, 'manifest did not change after open')
 
-      db.close(function (err) {
-        t.ifError(err, 'no close error')
-        t.same(db.supports, before, 'manifest did not change after close')
-        t.end()
-      })
-    })
+    await db.close()
+    t.same(db.supports, before, 'manifest did not change after close')
   })
 }