Add segfault tests (#514)

* restore (but skip) segfault test from abstract-leveldown

* prevent segfault when calling iterator() on non-open db

leveldown.js

@@ -88,6 +88,11 @@ LevelDOWN.prototype.getProperty = function (property) {
 }
 
 LevelDOWN.prototype._iterator = function (options) {
+  if (this.status !== 'open') {
+    // Prevent segfault
+    throw new Error('cannot call iterator() before open()')
+  }
+
   return new Iterator(this, options)
 }
 

test/segfault-test.js

@@ -0,0 +1,43 @@
+const test = require('tape')
+const testCommon = require('./common')
+
+// Open issue: https://github.com/Level/leveldown/issues/157
+test.skip('close() does not segfault if there is a pending write', function (t) {
+  t.plan(3)
+
+  const db = testCommon.factory()
+
+  db.open(function (err) {
+    t.ifError(err, 'no open error')
+
+    // The "sync" option seems to be a reliable way to trigger a segfault,
+    // but is not necessarily the cause of that segfault. More likely, it
+    // exposes a race condition that's already there.
+    db.put('foo', 'bar', { sync: true }, function (err) {
+      // We never get here, due to segfault.
+      t.ifError(err, 'no put error')
+    })
+
+    db.close(function (err) {
+      // We never get here, due to segfault.
+      t.ifError(err, 'no close error')
+    })
+  })
+})
+
+// See https://github.com/Level/leveldown/issues/134
+test('iterator() does not segfault if db is not open', function (t) {
+  t.plan(2)
+
+  const db = testCommon.factory()
+
+  try {
+    db.iterator()
+  } catch (err) {
+    t.is(err.message, 'cannot call iterator() before open()')
+  }
+
+  db.close(function (err) {
+    t.ifError(err, 'no close error')
+  })
+})