Test that empty range options are ignored

Cherry-picked from Level/leveldown#684

test/empty-range-option-test.js

@@ -0,0 +1,50 @@
+const test = require('tape')
+const concat = require('level-concat-iterator')
+const testCommon = require('./common')
+const rangeOptions = 'start end gt gte lt lte'.split(' ')
+
+test('empty range options are ignored', function (t) {
+  const db = testCommon.factory()
+
+  t.test('setup', function (t) {
+    db.open(function (err) {
+      t.ifError(err, 'no open error')
+
+      db.batch()
+        .put(Buffer.from([0]), 'value')
+        .put(Buffer.from([126]), 'value')
+        .write(t.end.bind(t))
+    })
+  })
+
+  rangeOptions.forEach(function (option) {
+    t.test(option, function (t) {
+      t.plan(8)
+
+      concat(db.iterator({ [option]: Buffer.alloc(0) }), verifyBuffer)
+      concat(db.iterator({ [option]: Buffer.alloc(0), keyAsBuffer: false }), verifyString)
+      concat(db.iterator({ [option]: '' }), verifyBuffer)
+      concat(db.iterator({ [option]: '', keyAsBuffer: false }), verifyString)
+
+      function verifyBuffer (err, entries) {
+        t.ifError(err, 'no concat error')
+        t.same(entries.map(getKey), [Buffer.from([0]), Buffer.from([126])])
+      }
+
+      function verifyString (err, entries) {
+        t.ifError(err, 'no concat error')
+        t.same(entries.map(getKey), ['\x00', '~'])
+      }
+
+      function getKey (entry) {
+        return entry.key
+      }
+    })
+  })
+
+  t.test('teardown', function (t) {
+    db.close(t.end.bind(t))
+  })
+
+  t.end()
+})