From 6a9011e2fee06e73d5710f10b0aff6317a6f098b Mon Sep 17 00:00:00 2001
From: alan bount <alan@zeroasterisk.com>
Date: Thu, 30 Jul 2015 13:33:49 -0400
Subject: [PATCH] Fix to fail gracefully if current version missing

Use Case:

Given developer has a branch with a new Migration version.
When the developer changes branch back to master/integration.
Then the Migration should not throw an Error, crashing Meteor.

Change _findIndexByVersion() to return false if not found.
Change test for index into _migrateTo(), start=graceful fail, end=error.
Add a new test to verify functionality.
---
 migrations_server.js | 34 ++++++++++++++++++++++------------
 migrations_tests.js  | 17 +++++++++++++++--
 package.js           |  2 +-
 3 files changed, 38 insertions(+), 15 deletions(-)

diff --git a/migrations_server.js b/migrations_server.js
index 152169a..69c5f06 100644
--- a/migrations_server.js
+++ b/migrations_server.js
@@ -84,7 +84,7 @@ Migrations.migrateTo = function(command) {
 
   // remember to run meteor with --once otherwise it will restart
   if (subcommand === 'exit')
-    process.exit(0); 
+    process.exit(0);
 }
 
 // just returns the current version
@@ -118,7 +118,18 @@ Migrations._migrateTo = function(version, rerun) {
   }
 
   var startIdx = this._findIndexByVersion(currentVersion);
+  if (typeof startIdx === 'boolean' && !startIdx) {
+    // fail gracefully, if the current version is not found
+    console.log('Not migrating, current version not found.');
+    return;
+  }
+
   var endIdx = this._findIndexByVersion(version);
+  if (typeof endIdx === 'boolean' && !endIdx) {
+    // throw error, if the destination version is not found
+    console.log('Not migrating, target version not found. (throwing error)');
+    throw new Meteor.Error('Can\'t find migration version ' + version);
+  }
 
   // console.log('startIdx:' + startIdx + ' endIdx:' + endIdx);
   console.log('Migrating from version ' + this._list[startIdx].version
@@ -127,17 +138,17 @@ Migrations._migrateTo = function(version, rerun) {
   // run the actual migration
   function migrate(direction, idx) {
     var migration = self._list[idx];
-    
+
     if (typeof migration[direction] !== 'function') {
-      throw new Meteor.Error('Cannot migrate ' + direction + ' on version ' 
+      throw new Meteor.Error('Cannot migrate ' + direction + ' on version '
         + migration.version);
     }
 
-    function maybeName() { 
+    function maybeName() {
       return migration.name ? ' (' + migration.name + ')' : '';
     }
 
-    console.log('Running ' + direction + '() on version ' 
+    console.log('Running ' + direction + '() on version '
       + migration.version + maybeName());
     migration[direction].call();
   }
@@ -166,7 +177,7 @@ Migrations._migrateTo = function(version, rerun) {
 }
 
 // gets the current control record, optionally creating it if non-existant
-Migrations._getControl = function() {  
+Migrations._getControl = function() {
   var control = this._collection.findOne({_id: 'control'});
 
   return control || this._setControl({version: 0, locked: false});
@@ -178,24 +189,23 @@ Migrations._setControl = function(control) {
   check(control.version, Number);
   check(control.locked, Boolean);
 
-  this._collection.update({_id: 'control'}, 
+  this._collection.update({_id: 'control'},
     {$set: {version: control.version, locked: control.locked}}, {upsert: true});
 
   return control;
 }
 
-// returns the migration index in _list or throws if not found
+// returns the migration index in _list or false
 Migrations._findIndexByVersion = function(version) {
   for (var i = 0;i < this._list.length;i++) {
     if (this._list[i].version === version)
-      return i; 
+      return i;
   }
-
-  throw new Meteor.Error('Can\'t find migration version ' + version);
+  return false;
 }
 
 //reset (mainly intended for tests)
 Migrations._reset = function() {
   this._list = [{version: 0, up: function(){}}];
   this._collection.remove({});
-}
\ No newline at end of file
+}
diff --git a/migrations_tests.js b/migrations_tests.js
index fbd01c5..02b4120 100644
--- a/migrations_tests.js
+++ b/migrations_tests.js
@@ -96,7 +96,7 @@ Tinytest.add('Tests migrating down to version 0', function(test) {
   Migrations._reset();
 
   test.equal(Migrations.getVersion(), 0);
-  
+
   Migrations.add({
     up: function () {run.push('u1');},
     down: function () {run.push('d1');},
@@ -163,4 +163,17 @@ Tinytest.add('Checks that rerun works correctly', function(test) {
   Migrations.migrateTo('1,rerun');
   test.equal(run, ['u1', 'u1']);
   test.equal(Migrations.getVersion(), 1);
-});
\ No newline at end of file
+});
+
+Tinytest.add('Checks that it fails gracefully if a current migration is missing', function(test) {
+  Migrations._reset();
+
+  // set the "current" version to a non-existent record, 999
+  Migrations._setControl({version: 999, locked: false});
+  test.equal(Migrations.getVersion(), 999);
+
+  // shouldnt do anything (no errors)
+  Migrations.migrateTo('latest');
+  test.equal(Migrations.getVersion(), 999);
+});
+
diff --git a/package.js b/package.js
index 6584124..ef7eedd 100644
--- a/package.js
+++ b/package.js
@@ -1,6 +1,6 @@
 Package.describe({
   summary: "Allows you to define and run db migrations.",
-  version: "0.7.4",
+  version: "0.7.5",
   name: "percolate:migrations",
   git: "https://github.com/percolatestudio/meteor-migrations.git"
 });