Fix incorrectly tenant default groups

When creating a tenant, if there are already groups in the database,
it would assign a random group.
This would manifest by having a seemingly random group assigned to newly
discovered VMs/Hosts. There can then be privilege issues as the admins
possibly don't have access to the group.

This only happens for customers who had a database before tenancy
was introduced in 2015. It incorrectly assigned during the migration
process in 20151021174140_assign_tenant_default_group

This also will probably only happen for the default tenant.

The fix: When a tenant points to a group that is not a tenant group,
change the default group to point to a new tenant group.
The old group was an incorrect group.

https://bugzilla.redhat.com/show_bug.cgi?id=1625788

I also changed the MiqGroup code to choose the correct group.

db/migrate/20180926152238_fix_default_tenant_group.rb

@@ -0,0 +1,56 @@
+class FixDefaultTenantGroup < ActiveRecord::Migration[5.0]
+  class Tenant < ActiveRecord::Base
+    belongs_to :default_miq_group, :class_name => "::FixDefaultTenantGroup::MiqGroup"
+
+    def add_default_miq_group
+      tenant_group = ::FixDefaultTenantGroup::MiqGroup.create_tenant_group(self)
+      update_attributes!(:default_miq_group_id => tenant_group.id)
+    end
+
+    def root?
+      ancestry.nil?
+    end
+  end
+
+  class MiqUserRole < ActiveRecord::Base
+    DEFAULT_TENANT_ROLE_NAME = "EvmRole-tenant_administrator".freeze
+
+    # if there is no role, that is ok
+    # MiqGroup.seed will populate
+
+    def self.default_tenant_role
+      @default_role ||= find_by(:name => DEFAULT_TENANT_ROLE_NAME)
+    end
+  end
+
+  class MiqGroup < ActiveRecord::Base
+    TENANT_GROUP = "tenant".freeze
+    USER_GROUP   = "user".freeze
+
+    def tenant_group?
+      group_type == TENANT_GROUP
+    end
+
+    def self.create_tenant_group(tenant)
+      role = ::FixDefaultTenantGroup::MiqUserRole.default_tenant_role
+      create_with(
+        :description      => "Tenant #{tenant.name} #{tenant.id} access",
+        :sequence         => 1,
+        :guid             => SecureRandom.uuid,
+        :miq_user_role_id => role.try(:id)
+      ).find_or_create_by!(
+        :tenant_id  => tenant.id,
+        :group_type => TENANT_GROUP,
+      )
+    end
+  end
+
+  def up
+    say_with_time "adding default tenant groups" do
+      Tenant.all.reject { |t| t.default_miq_group&.tenant_group? }.each do |t|
+        t.default_miq_group_id = nil
+        t.add_default_miq_group
+      end
+    end
+  end
+end

spec/migrations/20180926152238_fix_default_tenant_group_spec.rb

@@ -0,0 +1,39 @@
+require_migration
+
+describe FixDefaultTenantGroup do
+  let(:tenant_stub) { migration_stub(:Tenant) }
+  let(:group_stub)  { migration_stub(:MiqGroup) }
+  let(:role_stub)   { migration_stub(:MiqUserRole) }
+  let(:tenant_role) { role_stub.create!(:name => role_stub::DEFAULT_TENANT_ROLE_NAME) }
+
+  migration_context :up do
+    context "role exists" do
+      before do
+        tenant_role # make sure it exists
+      end
+
+      it "creates a new group" do
+        g = group_stub.create!(:group_type => group_stub::USER_GROUP)
+        t = tenant_stub.create!(:default_miq_group_id => g.id)
+        expect(t.default_miq_group).not_to be_tenant_group
+
+        migrate
+
+        t.reload
+        expect(t.default_miq_group).to be_tenant_group
+      end
+
+      it "keeps valid tenant groups" do
+        t = tenant_stub.create!
+        t.add_default_miq_group
+        g_id = t.default_miq_group_id
+        t.save
+
+        migrate
+
+        t.reload
+        expect(t.default_miq_group_id).to eq(g_id)
+      end
+    end
+  end
+end