Fix a bad error return in RA (letsencrypt#3061)

RA.NewRegistration checked for an error return from
SA.NewRegistration, but failed to properly propagate
the error. It was just setting the err variable and falling
through to the successful return case. This fixes that
issue and adds a unittest.

ra/ra.go

@@ -359,9 +359,7 @@ func (ra *RegistrationAuthorityImpl) NewRegistration(ctx context.Context, init c
 	// Store the authorization object, then return it
 	reg, err := ra.SA.NewRegistration(ctx, reg)
 	if err != nil {
-		// berrors.InternalServerError since the user-data was validated before being
-		// passed to the SA.
-		err = berrors.InternalServerError(err.Error())
+		return core.Registration{}, err
 	}
 
 	ra.stats.Inc("NewRegistrations", 1)

ra/ra_test.go

@@ -394,6 +394,30 @@ func TestNewRegistration(t *testing.T) {
 	test.Assert(t, core.KeyDigestEquals(reg.Key, AccountKeyB), "Retrieved registration differed.")
 }
 
+type mockSAFailsNewRegistration struct {
+	mocks.StorageAuthority
+}
+
+func (ms *mockSAFailsNewRegistration) NewRegistration(ctx context.Context, reg core.Registration) (core.Registration, error) {
+	return core.Registration{}, fmt.Errorf("too bad")
+}
+
+func TestNewRegistrationSAFailure(t *testing.T) {
+	_, _, ra, _, cleanUp := initAuthorities(t)
+	defer cleanUp()
+	ra.SA = &mockSAFailsNewRegistration{}
+	input := core.Registration{
+		Contact:   &[]string{"mailto:[email protected]"},
+		Key:       &AccountKeyB,
+		InitialIP: net.ParseIP("7.6.6.5"),
+	}
+
+	result, err := ra.NewRegistration(ctx, input)
+	if err == nil {
+		t.Fatalf("NewRegistration should have failed when SA.NewRegistration failed %#v", result.Key)
+	}
+}
+
 func TestNewRegistrationNoFieldOverwrite(t *testing.T) {
 	_, _, ra, _, cleanUp := initAuthorities(t)
 	defer cleanUp()