Added TestSelectUIDPasswordProvider to login flow tests.

This tests the code added to detect when the 'dcos-users' provider is
available and select it even if multiple providers are available.

Co-authored-by: Armand Grillet <armand.grillet@outlook.com>
Co-authored-by: Bilal Amarni <bilal.amarni@gmail.com>

pkg/login/flow_test.go

@@ -0,0 +1,41 @@
+package login
+
+import (
+	"testing"
+
+	"github.com/spf13/afero"
+	"github.com/stretchr/testify/require"
+)
+
+func TestSelectUIDPasswordProvider(t *testing.T) {
+	flow := NewFlow(FlowOpts{})
+	flow.flags = NewFlags(afero.NewMemMapFs(), nil, nil)
+	flow.flags.username = "hello"
+	flow.flags.password = "itsme"
+
+	providers := Providers{}
+
+	providers["login-provider-1"] = &Provider{
+		ID:           "login-provider-1",
+		Type:         DCOSUIDPassword,
+		Description:  "Default DC/OS login provider",
+		ClientMethod: methodUserCredential,
+		Config: ProviderConfig{
+			StartFlowURL: "/acs/api/v1/auth/login",
+		},
+	}
+
+	providers["login-provider-2"] = &Provider{
+		ID:           "login-provider-2",
+		Type:         DCOSUIDPassword,
+		Description:  "Default DC/OS login provider",
+		ClientMethod: methodUserCredential,
+		Config: ProviderConfig{
+			StartFlowURL: "/acs/api/v1/auth/login",
+		},
+	}
+
+	provider, err := flow.selectProvider(providers)
+	require.NoError(t, err)
+	require.True(t, provider == providers["login-provider-1"] || provider == providers["login-provider-2"])
+}