Return promise on cursor end (#2589)

* Return promise on cursor end

* Remove redudant if

Author: brianc

Diff for: packages/pg-cursor/index.js

@@ -208,20 +208,15 @@ class Cursor extends EventEmitter {
     }
 
     if (!this.connection || this.state === 'done') {
-      if (cb) {
-        return setImmediate(cb)
-      } else {
-        return
-      }
+      setImmediate(cb)
+      return promise
     }
 
     this._closePortal()
     this.state = 'done'
-    if (cb) {
-      this.connection.once('readyForQuery', function () {
-        cb()
-      })
-    }
+    this.connection.once('readyForQuery', function () {
+      cb()
+    })
 
     // Return the promise (or undefined)
     return promise

Diff for: packages/pg-cursor/test/close.js

@@ -23,6 +23,17 @@ describe('close', function () {
     })
   })
 
+  it('can close a finished cursor a promise', function (done) {
+    const cursor = new Cursor(text)
+    this.client.query(cursor)
+    cursor.read(100, (err) => {
+      assert.ifError(err)
+      cursor.close().then(() => {
+        this.client.query('SELECT NOW()', done)
+      })
+    })
+  })
+
   it('closes cursor early', function (done) {
     const cursor = new Cursor(text)
     this.client.query(cursor)