diff --git a/leveldown.js b/leveldown.js
index e6b64b66..ce2e1236 100644
--- a/leveldown.js
+++ b/leveldown.js
@@ -53,7 +53,21 @@ LevelDOWN.prototype._batch = function (operations, options, callback) {
 }
 
 
-LevelDOWN.prototype._approximateSize = function (start, end, callback) {
+LevelDOWN.prototype.approximateSize = function (start, end, callback) {
+  if (start == null ||
+      end == null ||
+      typeof start === 'function' ||
+      typeof end === 'function') {
+    throw new Error('approximateSize() requires valid `start`, `end` and `callback` arguments')
+  }
+
+  if (typeof callback !== 'function') {
+    throw new Error('approximateSize() requires a callback argument')
+  }
+
+  start = this._serializeKey(start)
+  end = this._serializeKey(end)
+
   this.binding.approximateSize(start, end, callback)
 }
 
diff --git a/package.json b/package.json
index 232e5d3a..876df2e8 100644
--- a/package.json
+++ b/package.json
@@ -32,7 +32,7 @@
   "main": "leveldown.js",
   "typings": "leveldown.d.ts",
   "dependencies": {
-    "abstract-leveldown": "~3.0.0",
+    "abstract-leveldown": "~4.0.0",
     "bindings": "~1.3.0",
     "fast-future": "~1.0.2",
     "nan": "~2.8.0",
diff --git a/test/approximate-size-test.js b/test/approximate-size-test.js
index 31038a48..0e662d64 100644
--- a/test/approximate-size-test.js
+++ b/test/approximate-size-test.js
@@ -1,6 +1,123 @@
-const test       = require('tape')
-    , testCommon = require('abstract-leveldown/testCommon')
-    , leveldown  = require('../')
-    , abstract   = require('abstract-leveldown/abstract/approximate-size-test')
+const test = require('tape')
+const leveldown = require('..')
+const testCommon = require('abstract-leveldown/testCommon')
 
-abstract.all(leveldown, test, testCommon)
+var db
+
+test('setUp common for approximate size', testCommon.setUp)
+
+test('setUp db', function (t) {
+  db = leveldown(testCommon.location())
+  console.log('db', db)
+  db.open(t.end.bind(t))
+})
+
+test('test argument-less approximateSize() throws', function (t) {
+  t.throws(
+    db.approximateSize.bind(db)
+    , { name: 'Error', message: 'approximateSize() requires valid `start`, `end` and `callback` arguments' }
+    , 'no-arg approximateSize() throws'
+  )
+  t.end()
+})
+
+test('test callback-less, 1-arg, approximateSize() throws', function (t) {
+  t.throws(
+    db.approximateSize.bind(db, 'foo')
+    , { name: 'Error', message: 'approximateSize() requires valid `start`, `end` and `callback` arguments' }
+    , 'callback-less, 1-arg approximateSize() throws'
+  )
+  t.end()
+})
+
+test('test callback-less, 2-arg, approximateSize() throws', function (t) {
+  t.throws(
+    db.approximateSize.bind(db, 'foo', 'bar')
+    , { name: 'Error', message: 'approximateSize() requires a callback argument' }
+    , 'callback-less, 2-arg approximateSize() throws'
+  )
+  t.end()
+})
+
+test('test callback-less, 3-arg, approximateSize() throws', function (t) {
+  t.throws(
+    db.approximateSize.bind(db, function () {})
+    , { name: 'Error', message: 'approximateSize() requires valid `start`, `end` and `callback` arguments' }
+    , 'callback-only approximateSize() throws'
+  )
+  t.end()
+})
+
+test('test callback-only approximateSize() throws', function (t) {
+  t.throws(
+    db.approximateSize.bind(db, function () {})
+    , { name: 'Error', message: 'approximateSize() requires valid `start`, `end` and `callback` arguments' }
+    , 'callback-only approximateSize() throws'
+  )
+  t.end()
+})
+
+test('test 1-arg + callback approximateSize() throws', function (t) {
+  t.throws(
+    db.approximateSize.bind(db, 'foo', function () {})
+    , { name: 'Error', message: 'approximateSize() requires valid `start`, `end` and `callback` arguments' }
+    , '1-arg + callback approximateSize() throws'
+  )
+  t.end()
+})
+
+test('test custom _serialize*', function (t) {
+  t.plan(4)
+  var db = leveldown(testCommon.location())
+  db._serializeKey = function (data) { return data }
+  db.approximateSize = function (start, end, callback) {
+    t.deepEqual(start, { foo: 'bar' })
+    t.deepEqual(end, { beep: 'boop' })
+    process.nextTick(callback)
+  }
+  db.open(function () {
+    db.approximateSize({ foo: 'bar' }, { beep: 'boop' }, function (err) {
+      t.error(err)
+      db.close(t.error.bind(t))
+    })
+  })
+})
+
+test('test approximateSize()', function (t) {
+  var data = Array.apply(null, Array(10000)).map(function () {
+    return 'aaaaaaaaaa'
+  }).join('')
+
+  db.batch(Array.apply(null, Array(10)).map(function (x, i) {
+    return { type: 'put', key: 'foo' + i, value: data }
+  }), function (err) {
+    t.error(err)
+
+    // cycle open/close to ensure a pack to .sst
+
+    db.close(function (err) {
+      t.error(err)
+
+      db.open(function (err) {
+        t.error(err)
+
+        db.approximateSize('!', '~', function (err, size) {
+          t.error(err)
+
+          t.equal(typeof size, 'number')
+          // account for snappy compression, original would be ~100000
+          t.ok(size > 40000, 'size reports a reasonable amount (' + size + ')')
+
+          db.close(function (err) {
+            t.error(err)
+            t.end()
+          })
+        })
+      })
+    })
+  })
+})
+
+test('tearDown', function (t) {
+  db.close(testCommon.tearDown.bind(null, t))
+})
diff --git a/test/batch-test.js b/test/batch-test.js
index c93e6eff..903eadc3 100644
--- a/test/batch-test.js
+++ b/test/batch-test.js
@@ -1,6 +1,5 @@
 const test       = require('tape')
-    , testCommon = require('abstract-leveldown/testCommon')
-    , leveldown  = require('../')
+    , leveldown  = require('..')
     , abstract   = require('abstract-leveldown/abstract/batch-test')
 
-abstract.all(leveldown, test, testCommon)
+abstract.all(leveldown, test)
diff --git a/test/chained-batch-test.js b/test/chained-batch-test.js
index cc20f9e4..efe8e22a 100644
--- a/test/chained-batch-test.js
+++ b/test/chained-batch-test.js
@@ -1,6 +1,5 @@
 const test       = require('tape')
-    , testCommon = require('abstract-leveldown/testCommon')
-    , leveldown  = require('../')
+    , leveldown  = require('..')
     , abstract   = require('abstract-leveldown/abstract/chained-batch-test')
 
-abstract.all(leveldown, test, testCommon)
+abstract.all(leveldown, test)
diff --git a/test/cleanup-hanging-iterators-test.js b/test/cleanup-hanging-iterators-test.js
index 3ed394e6..01793783 100644
--- a/test/cleanup-hanging-iterators-test.js
+++ b/test/cleanup-hanging-iterators-test.js
@@ -1,6 +1,5 @@
 const test       = require('tape')
-    , testCommon = require('abstract-leveldown/testCommon')
-    , leveldown  = require('../')
+    , leveldown  = require('..')
     , makeTest   = require('./make')
 
 makeTest('test ended iterator', function (db, t, done) {
diff --git a/test/close-test.js b/test/close-test.js
index ae5d3bf8..a1030a3d 100644
--- a/test/close-test.js
+++ b/test/close-test.js
@@ -1,6 +1,6 @@
 const test       = require('tape')
     , testCommon = require('abstract-leveldown/testCommon')
-    , leveldown  = require('../')
+    , leveldown  = require('..')
     , abstract   = require('abstract-leveldown/abstract/close-test')
 
 module.exports.setUp = function () {
diff --git a/test/compact-range-test.js b/test/compact-range-test.js
index 135029af..94baca5d 100644
--- a/test/compact-range-test.js
+++ b/test/compact-range-test.js
@@ -1,6 +1,6 @@
 const test       = require('tape')
     , testCommon = require('abstract-leveldown/testCommon')
-    , leveldown  = require('../')
+    , leveldown  = require('..')
 
 var db
 
@@ -35,3 +35,7 @@ test('test compactRange() frees disk space after key deletion', function (t) {
     });
   });
 });
+
+test('tearDown', function (t) {
+  db.close(testCommon.tearDown.bind(null, t));
+});
diff --git a/test/compression-test.js b/test/compression-test.js
index 91c28eb7..2c8101b2 100644
--- a/test/compression-test.js
+++ b/test/compression-test.js
@@ -7,7 +7,7 @@ var async      = require('async')
   , du         = require('du')
   , delayed    = require('delayed')
   , common     = require('abstract-leveldown/testCommon')
-  , leveldown  = require('../')
+  , leveldown  = require('..')
   , test       = require('tape')
 
   , compressableData = new Buffer(Array.apply(null, Array(1024 * 100)).map(function () { return 'aaaaaaaaaa' }).join(''))
diff --git a/test/data/testdata.bin b/test/data/testdata.bin
deleted file mode 100644
index 59229b94..00000000
Binary files a/test/data/testdata.bin and /dev/null differ
diff --git a/test/del-test.js b/test/del-test.js
index b21712be..fc140dd9 100644
--- a/test/del-test.js
+++ b/test/del-test.js
@@ -1,6 +1,5 @@
 const test       = require('tape')
-    , testCommon = require('abstract-leveldown/testCommon')
-    , leveldown  = require('../')
+    , leveldown  = require('..')
     , abstract   = require('abstract-leveldown/abstract/del-test')
 
-abstract.all(leveldown, test, testCommon)
+abstract.all(leveldown, test)
diff --git a/test/destroy-test.js b/test/destroy-test.js
index d1be840e..4181ee6e 100644
--- a/test/destroy-test.js
+++ b/test/destroy-test.js
@@ -3,8 +3,7 @@ const test         = require('tape')
     , path         = require('path')
     , mkfiletree   = require('mkfiletree')
     , readfiletree = require('readfiletree')
-    , testCommon   = require('abstract-leveldown/testCommon')
-    , leveldown    = require('../')
+    , leveldown    = require('..')
     , makeTest     = require('./make')
 
 test('test argument-less destroy() throws', function (t) {
diff --git a/test/get-test.js b/test/get-test.js
index 52270ad3..8df01706 100644
--- a/test/get-test.js
+++ b/test/get-test.js
@@ -1,6 +1,5 @@
 const test       = require('tape')
-    , testCommon = require('abstract-leveldown/testCommon')
-    , leveldown  = require('../')
+    , leveldown  = require('..')
     , abstract   = require('abstract-leveldown/abstract/get-test')
 
-abstract.all(leveldown, test, testCommon)
+abstract.all(leveldown, test)
diff --git a/test/getproperty-test.js b/test/getproperty-test.js
index 46bce118..62e99d70 100644
--- a/test/getproperty-test.js
+++ b/test/getproperty-test.js
@@ -1,6 +1,6 @@
 const test       = require('tape')
     , testCommon = require('abstract-leveldown/testCommon')
-    , leveldown  = require('../')
+    , leveldown  = require('..')
 
 var db
 
diff --git a/test/iterator-range-test.js b/test/iterator-range-test.js
new file mode 100644
index 00000000..c6a2a164
--- /dev/null
+++ b/test/iterator-range-test.js
@@ -0,0 +1,5 @@
+const test       = require('tape')
+    , leveldown  = require('..')
+    , abstract   = require('abstract-leveldown/abstract/iterator-range-test')
+
+abstract.all(leveldown, test)
diff --git a/test/iterator-recursion-test.js b/test/iterator-recursion-test.js
index 716626ec..884e75ee 100644
--- a/test/iterator-recursion-test.js
+++ b/test/iterator-recursion-test.js
@@ -1,6 +1,6 @@
 const test          = require('tape')
     , testCommon    = require('abstract-leveldown/testCommon')
-    , leveldown     = require('../')
+    , leveldown     = require('..')
     , child_process = require('child_process') 
 
 var db
diff --git a/test/iterator-test.js b/test/iterator-test.js
index 21f2ce79..7c3064cb 100644
--- a/test/iterator-test.js
+++ b/test/iterator-test.js
@@ -1,13 +1,12 @@
 const test       = require('tape')
-    , testCommon = require('abstract-leveldown/testCommon')
-    , leveldown  = require('../')
+    , leveldown  = require('..')
     , abstract   = require('abstract-leveldown/abstract/iterator-test')
     , make       = require('./make')
     , iota       = require('iota-array')
     , lexi       = require('lexicographic-integer')
     , util       = require('util')
 
-abstract.all(leveldown, test, testCommon)
+abstract.all(leveldown, test)
 
 make('iterator throws if key is not a string or buffer', function (db, t, done) {
   var keys = [null, undefined, 1, true, false]
@@ -288,4 +287,4 @@ function not (n) {
 
 function even (n) {
   return n % 2 === 0
-}
\ No newline at end of file
+}
diff --git a/test/leveldown-test.js b/test/leveldown-test.js
index 11db1c38..dc005fc0 100644
--- a/test/leveldown-test.js
+++ b/test/leveldown-test.js
@@ -1,5 +1,5 @@
 const test      = require('tape')
-    , leveldown = require('../')
+    , leveldown = require('..')
     , abstract  = require('abstract-leveldown/abstract/leveldown-test')
 
 abstract.args(leveldown, test)
diff --git a/test/make.js b/test/make.js
index aeccf3b4..1ed47ee4 100644
--- a/test/make.js
+++ b/test/make.js
@@ -1,35 +1,40 @@
-const test       = require('tape')
-    , testCommon = require('abstract-leveldown/testCommon')
-    , cleanup    = testCommon.cleanup
-    , location   = testCommon.location
-    , leveldown  = require('../')
+const test = require('tape')
+const testCommon = require('abstract-leveldown/testCommon')
+const cleanup = testCommon.cleanup
+const leveldown = require('..')
 
 function makeTest (name, testFn) {
   test(name, function (t) {
-    cleanup(function () {
-      var loc  = location()
-        , db   = leveldown(loc)
-        , done = function (close) {
-            if (close === false)
-              return cleanup(t.end.bind(t))
-            db.close(function (err) {
-              t.notOk(err, 'no error from close()')
-              cleanup(t.end.bind(t))
-            })
-          }
+    cleanup(function (err) {
+      t.error(err, 'no error after cleanup')
+      var location = testCommon.location()
+      var db = leveldown(location)
+      var done = function (close) {
+        if (close === false) {
+          cleanup(function (err) {
+            t.error(err, 'no error after cleanup')
+            t.end()
+          })
+          return
+        }
+        db.close(function (err) {
+          t.error(err, 'no error from close()')
+          cleanup(function (err) {
+            t.error(err, 'no error after cleanup')
+            t.end()
+          })
+        })
+      }
       db.open(function (err) {
-       t.notOk(err, 'no error from open()')
-        db.batch(
-            [
-                { type: 'put', key: 'one', value: '1' }
-              , { type: 'put', key: 'two', value: '2' }
-              , { type: 'put', key: 'three', value: '3' }
-            ]
-          , function (err) {
-              t.notOk(err, 'no error from batch()')
-              testFn(db, t, done, loc)
-            }
-        )
+        t.error(err, 'no error from open()')
+        db.batch([
+          { type: 'put', key: 'one', value: '1' },
+          { type: 'put', key: 'two', value: '2' },
+          { type: 'put', key: 'three', value: '3' }
+        ], function (err) {
+          t.error(err, 'no error from batch()')
+          testFn(db, t, done, location)
+        })
       })
     })
   })
diff --git a/test/open-test.js b/test/open-test.js
index 0da638a3..bd5ad06c 100644
--- a/test/open-test.js
+++ b/test/open-test.js
@@ -1,6 +1,5 @@
 const test       = require('tape')
-    , testCommon = require('abstract-leveldown/testCommon')
-    , leveldown  = require('../')
+    , leveldown  = require('..')
     , abstract   = require('abstract-leveldown/abstract/open-test')
 
-abstract.all(leveldown, test, testCommon)
+abstract.all(leveldown, test)
diff --git a/test/put-get-del-test.js b/test/put-get-del-test.js
index 0f688585..56cd272e 100644
--- a/test/put-get-del-test.js
+++ b/test/put-get-del-test.js
@@ -1,9 +1,5 @@
 const test       = require('tape')
-    , testCommon = require('abstract-leveldown/testCommon')
-    , leveldown  = require('../')
-    , fs         = require('fs')
-    , path       = require('path')
-    , testBuffer = fs.readFileSync(path.join(__dirname, 'data/testdata.bin'))
+    , leveldown  = require('..')
     , abstract   = require('abstract-leveldown/abstract/put-get-del-test')
 
-abstract.all(leveldown, test, testCommon, testBuffer)
+abstract.all(leveldown, test)
diff --git a/test/put-test.js b/test/put-test.js
index e437f5ee..43bc438c 100644
--- a/test/put-test.js
+++ b/test/put-test.js
@@ -1,6 +1,5 @@
 const test       = require('tape')
-    , testCommon = require('abstract-leveldown/testCommon')
-    , leveldown  = require('../')
+    , leveldown  = require('..')
     , abstract   = require('abstract-leveldown/abstract/put-test')
 
-abstract.all(leveldown, test, testCommon)
+abstract.all(leveldown, test)
diff --git a/test/ranges-test.js b/test/ranges-test.js
deleted file mode 100644
index 7f16a2d0..00000000
--- a/test/ranges-test.js
+++ /dev/null
@@ -1,6 +0,0 @@
-const test       = require('tape')
-    , testCommon = require('abstract-leveldown/testCommon')
-    , leveldown  = require('../')
-    , abstract   = require('abstract-leveldown/abstract/ranges-test')
-
-abstract.all(leveldown, test, testCommon)
diff --git a/test/repair-test.js b/test/repair-test.js
index c878bdeb..8cc56879 100644
--- a/test/repair-test.js
+++ b/test/repair-test.js
@@ -3,8 +3,7 @@ const test         = require('tape')
     , path         = require('path')
     , mkfiletree   = require('mkfiletree')
     , readfiletree = require('readfiletree')
-    , testCommon   = require('abstract-leveldown/testCommon')
-    , leveldown    = require('../')
+    , leveldown    = require('..')
     , makeTest     = require('./make')
 
 test('test argument-less repair() throws', function (t) {
diff --git a/test/stack-blower.js b/test/stack-blower.js
index 00c48e1e..8c151f12 100644
--- a/test/stack-blower.js
+++ b/test/stack-blower.js
@@ -6,7 +6,7 @@
   * directly, we check for a command-line argument.
   */
 const testCommon = require('abstract-leveldown/testCommon')
-    , leveldown  = require('../')
+    , leveldown  = require('..')
 
 if (process.argv[2] == 'run') {
   testCommon.cleanup(function () {