Add manifest (Level/community#83)

abstract-leveldown.js

@@ -4,8 +4,52 @@ var AbstractChainedBatch = require('./abstract-chained-batch')
 var hasOwnProperty = Object.prototype.hasOwnProperty
 var rangeOptions = 'start end gt gte lt lte'.split(' ')
 
-function AbstractLevelDOWN () {
+function AbstractLevelDOWN (supports) {
+  // TODO (next major): make this mandatory
+  if (!supports || typeof supports !== 'object') supports = {}
+
   this.status = 'new'
+
+  // TODO (after review): move this to a module for reuse by levelup
+  this.supports = xtend(supports, {
+    // Features of abstract-leveldown
+    bufferKeys: !!supports.bufferKeys,
+    snapshots: !!supports.snapshots,
+    permanence: !!supports.permanence,
+    seek: !!supports.seek,
+
+    // Features of abstract-leveldown that levelup doesn't have
+    status: !!supports.status,
+
+    // Experimental features
+    clear: !!supports.clear,
+    type: !!supports.type,
+
+    // Features of disk-based implementations
+    createIfMissing: !!supports.createIfMissing,
+    errorIfExists: !!supports.errorIfExists,
+
+    // Features of level(up) that abstract-leveldown doesn't have yet
+    deferredOpen: !!supports.deferredOpen,
+    openCallback: !!supports.openCallback,
+    promises: !!supports.promises,
+    streams: !!supports.streams,
+    encodings: !!supports.encodings,
+
+    // Methods that are not part of abstract-leveldown or levelup
+    additionalMethods: supports.additionalMethods || {
+      // Example
+      // approximateSize: {
+      //   sync: false,
+      //   callback: true,
+      //   promise: false
+      // },
+      // createWriteStream: {
+      //   sync: true,
+      //   writable: true
+      // }
+    }
+  })
 }
 
 AbstractLevelDOWN.prototype.open = function (options, callback) {

test/common.js

@@ -13,8 +13,12 @@ function testCommon (options) {
   return {
     test: test,
     factory: factory,
+
+    // TODO (next major): remove
     setUp: options.setUp || noopTest(),
     tearDown: options.tearDown || noopTest(),
+
+    // TODO (next major): use db.supports instead
     bufferKeys: options.bufferKeys !== false,
     createIfMissing: options.createIfMissing !== false,
     errorIfExists: options.errorIfExists !== false,

test/index.js

@@ -5,6 +5,7 @@ function suite (options) {
   var test = testCommon.test
 
   require('./factory-test')(test, testCommon)
+  require('./manifest-test')(test, testCommon)
 
   require('./leveldown-test')(test, testCommon)
   require('./open-test').all(test, testCommon)

test/manifest-test.js

@@ -0,0 +1,47 @@
+var xtend = require('xtend')
+var hasOwnProperty = Object.prototype.hasOwnProperty
+
+module.exports = function (test, testCommon) {
+  test('setUp common', testCommon.setUp)
+
+  test('db has manifest', function (t) {
+    var db = testCommon.factory()
+    var supports = db.supports
+
+    t.ok(isObject(supports))
+    t.ok(isObject(supports.additionalMethods))
+
+    for (var k in supports) {
+      if (!hasOwnProperty.call(supports, k)) continue
+      if (k === 'additionalMethods') continue
+
+      t.is(typeof supports[k], 'boolean', k)
+    }
+
+    for (var m in supports.additionalMethods) {
+      if (!hasOwnProperty.call(supports.additionalMethods, m)) continue
+      t.ok(isObject(supports.additionalMethods[m]), m)
+    }
+
+    var before = xtend(supports, {
+      additionalMethods: xtend(supports.additionalMethods)
+    })
+
+    db.open(function (err) {
+      t.ifError(err, 'no open error')
+      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()
+      })
+    })
+  })
+
+  test('tearDown', testCommon.tearDown)
+}
+
+function isObject (o) {
+  return typeof o === 'object' && o !== null
+}

test/self.js

@@ -22,7 +22,7 @@ var legacyRangeOptions = ['start', 'end']
 // excluding noop operations that can't pass the test suite.
 
 require('./leveldown-test')(test, testCommon)
-
+require('./manifest-test')(test, testCommon)
 require('./open-test').all(test, testCommon)
 
 require('./open-create-if-missing-test').setUp(test, testCommon)