Merge pull request #3904 from MetaMask/migrations-template

meta - create a migration template

app/scripts/migrations/template.js

@@ -0,0 +1,29 @@
+// next version number
+const version = 0
+
+/*
+
+description of migration and what it does
+
+*/
+
+const clone = require('clone')
+
+module.exports = {
+  version,
+
+  migrate: async function (originalVersionedData) {
+    const versionedData = clone(originalVersionedData)
+    versionedData.meta.version = version
+    const state = versionedData.data
+    const newState = transformState(state)
+    versionedData.data = newState
+    return versionedData
+  },
+}
+
+function transformState (state) {
+  const newState = state
+  // transform state here
+  return newState
+}

test/unit/migrations/template-test.js

@@ -0,0 +1,17 @@
+const assert = require('assert')
+const migrationTemplate = require('../../../app/scripts/migrations/template')
+const properTime = (new Date()).getTime()
+const storage = {
+  meta: {},
+  data: {},
+}
+
+describe('storage is migrated successfully', () => {
+  it('should work', (done) => {
+    migrationTemplate.migrate(storage)
+    .then((migratedData) => {
+      assert.equal(migratedData.meta.version, 0)
+      done()
+    }).catch(done)
+  })
+})