Initial import with skill sheet working

node_modules/abstract-level/test/iterator-snapshot-test.js

@@ -0,0 +1,99 @@
+'use strict'
+
+exports.snapshot = function (test, testCommon) {
+  function make (run) {
+    return function (t) {
+      const db = testCommon.factory()
+
+      db.open(function (err) {
+        t.ifError(err, 'no open error')
+
+        db.put('z', 'from snapshot', function (err) {
+          t.ifError(err, 'no put error')
+
+          // For this test it is important that we don't read eagerly.
+          // NOTE: highWaterMarkBytes is not an abstract option, but
+          // it is supported by classic-level and others. Also set the
+          // old & equivalent leveldown highWaterMark option for compat.
+          const it = db.iterator({ highWaterMarkBytes: 0, highWaterMark: 0 })
+
+          run(t, db, it, function end (err) {
+            t.ifError(err, 'no run error')
+
+            it.close(function (err) {
+              t.ifError(err, 'no iterator close error')
+              db.close(t.end.bind(t))
+            })
+          })
+        })
+      })
+    }
+  }
+
+  test('delete key after snapshotting', make(function (t, db, it, end) {
+    db.del('z', function (err) {
+      t.ifError(err, 'no del error')
+
+      it.next(function (err, key, value) {
+        t.ifError(err, 'no next error')
+        t.ok(key, 'got a key')
+        t.is(key.toString(), 'z', 'correct key')
+        t.is(value.toString(), 'from snapshot', 'correct value')
+
+        end()
+      })
+    })
+  }))
+
+  test('overwrite key after snapshotting', make(function (t, db, it, end) {
+    db.put('z', 'not from snapshot', function (err) {
+      t.ifError(err, 'no put error')
+
+      it.next(function (err, key, value) {
+        t.ifError(err, 'no next error')
+        t.ok(key, 'got a key')
+        t.is(key.toString(), 'z', 'correct key')
+        t.is(value.toString(), 'from snapshot', 'correct value')
+
+        end()
+      })
+    })
+  }))
+
+  test('add key after snapshotting that sorts first', make(function (t, db, it, end) {
+    db.put('a', 'not from snapshot', function (err) {
+      t.ifError(err, 'no put error')
+
+      it.next(function (err, key, value) {
+        t.ifError(err, 'no next error')
+
+        t.ok(key, 'got a key')
+        t.is(key.toString(), 'z', 'correct key')
+        t.is(value.toString(), 'from snapshot', 'correct value')
+
+        end()
+      })
+    })
+  }))
+
+  // NOTE: adapted from memdown
+  test('delete key after snapshotting, with more entries available', async function (t) {
+    const db = testCommon.factory()
+    await db.open()
+    await Promise.all([db.put('a', 'A'), db.put('b', 'B'), db.put('c', 'C')])
+
+    const iterator = db.iterator({ gte: 'a' })
+    t.same(await iterator.next(), ['a', 'A'])
+
+    await db.del('b')
+    t.same(await iterator.next(), ['b', 'B'])
+    t.same(await iterator.next(), ['c', 'C'])
+
+    await iterator.close()
+    return db.close()
+  })
+}
+
+exports.all = function (test, testCommon) {
+  exports.snapshot(test, testCommon)
+}