diff --git a/testing/provisioner.go b/testing/provisioner.go
index <HASH>..<HASH> 100644
--- a/testing/provisioner.go
+++ b/testing/provisioner.go
@@ -92,6 +92,10 @@ func (a *FakeApp) ProvisionUnits() []provision.AppUnit {
 	return a.units
 }
 
+func (a *FakeApp) AddUnit(u *FakeUnit) {
+	a.units = append(a.units, u)
+}
+
 func (a *FakeApp) SetUnitStatus(s provision.Status, index int) {
 	if index < len(a.units) {
 		a.units[index].(*FakeUnit).Status = s
diff --git a/testing/provisioner_test.go b/testing/provisioner_test.go
index <HASH>..<HASH> 100644
--- a/testing/provisioner_test.go
+++ b/testing/provisioner_test.go
@@ -20,6 +20,12 @@ type S struct{}
 
 var _ = gocheck.Suite(&S{})
 
+func (s *S) TestFakeAppAddUnit(c *gocheck.C) {
+	app := NewFakeApp("jean", "mj", 0)
+	app.AddUnit(&FakeUnit{Name: "jean/0"})
+	c.Assert(app.units, gocheck.HasLen, 1)
+}
+
 func (s *S) TestFindApp(c *gocheck.C) {
 	app := NewFakeApp("red-sector", "rush", 1)
 	p := NewFakeProvisioner()
testing/provisioner: added method to add units to a fake app