(POOLER-73) Restructure tests to unit and integration directories

Previously all of the spec tests for VM Pooler were all together in the specs
directory.  However some tests require a working local Redis server to operate
and other instead mock all external dependencies.  This commit splits the test
files between unit and integration, where integration tests require a working
Redis instance, and unit tests do not.  This commit also removes the root
`vmpooler` directory as it is not required.  The tests rake test still operates
correctly.

This commit also adds the mock_redis library for testing for the pool_manager.

spec/unit/pool_manager_migration_spec.rb

@@ -0,0 +1,87 @@
+require 'spec_helper'
+require 'mock_redis'
+require 'time'
+
+describe 'Pool Manager' do
+  let(:logger) { double('logger') }
+  let(:redis) { MockRedis.new }
+  let(:metrics) { Vmpooler::DummyStatsd.new }
+  let(:config) {
+    {
+      config: {
+        'site_name' => 'test pooler',
+        'migration_limit' => 2,
+        vsphere: {
+          'server' => 'vsphere.puppet.com',
+          'username' => 'vmpooler@vsphere.local',
+          'password' => '',
+          'insecure' => true
+        },
+        pools: [ {'name' => 'pool1', 'size' => 5, 'folder' => 'pool1_folder'} ],
+        statsd: { 'prefix' => 'stats_prefix'},
+        pool_names: [ 'pool1' ]
+      }
+    }
+  }
+  let(:pool) { config[:config][:pools][0]['name'] }
+  let(:vm) {
+    {
+      'name' => 'vm1',
+      'host' => 'host1',
+      'template' => pool,
+    }
+  }
+
+  describe '#_migrate_vm' do
+    let(:vsphere) { double(pool) }
+    let(:pooler) { Vmpooler::PoolManager.new(config, logger, redis, metrics) }
+    context 'evaluates VM for migration and logs host' do
+      before do
+        create_migrating_vm vm['name'], pool, redis
+        allow(vsphere).to receive(:find_vm).and_return(vm)
+        allow(pooler).to receive(:get_vm_host_info).and_return([{'name' => 'host1'}, 'host1'])
+      end
+
+      it 'logs VM host when migration is disabled' do
+        config[:config]['migration_limit'] = nil
+
+        expect(redis.sismember("vmpooler__migrating__#{pool}", vm['name'])).to be true
+        expect(logger).to receive(:log).with('s', "[ ] [#{pool}] '#{vm['name']}' is running on #{vm['host']}")
+
+        pooler._migrate_vm(vm['name'], pool, vsphere)
+
+        expect(redis.sismember("vmpooler__migrating__#{pool}", vm['name'])).to be false
+      end
+
+      it 'verifies that migration_limit greater than or equal to migrations in progress and logs host' do
+        add_vm_to_migration_set vm['name'], redis
+        add_vm_to_migration_set 'vm2', redis
+
+        expect(logger).to receive(:log).with('s', "[ ] [#{pool}] '#{vm['name']}' is running on #{vm['host']}. No migration will be evaluated since the migration_limit has been reached")
+
+        pooler._migrate_vm(vm['name'], pool, vsphere)
+      end
+
+      it 'verifies that migration_limit is less than migrations in progress and logs old host, new host and migration time' do
+        allow(vsphere).to receive(:find_least_used_compatible_host).and_return([{'name' => 'host2'}, 'host2'])
+        allow(vsphere).to receive(:migrate_vm_host)
+
+        expect(redis.hget("vmpooler__vm__#{vm['name']}", 'migration_time'))
+        expect(redis.hget("vmpooler__vm__#{vm['name']}", 'checkout_to_migration'))
+        expect(logger).to receive(:log).with('s', "[>] [#{pool}] '#{vm['name']}' migrated from #{vm['host']} to host2 in 0.00 seconds")
+
+        pooler._migrate_vm(vm['name'], pool, vsphere)
+      end
+
+      it 'fails when no suitable host can be found' do
+        error = 'ArgumentError: No target host found'
+        allow(vsphere).to receive(:find_least_used_compatible_host)
+        allow(vsphere).to receive(:migrate_vm_host).and_raise(error)
+
+        expect(logger).to receive(:log).with('s', "[x] [#{pool}] '#{vm['name']}' migration failed with an error: #{error}")
+
+        pooler._migrate_vm(vm['name'], pool, vsphere)
+      end
+    end
+  end
+end