test: add unit-test for machine config validation

Follow-up for #3383

I added couple of first tests, we should add more as we go through this
code. Even with those tests, I found and fixed two more panics.

Signed-off-by: Andrey Smirnov <smirnov.andrey@gmail.com>

pkg/machinery/config/types/v1alpha1/v1alpha1_validation.go

@@ -64,6 +64,8 @@ func (c *Config) Validate(mode config.RuntimeMode, options ...config.ValidationO
 
 	if c.MachineConfig == nil {
 		result = multierror.Append(result, errors.New("machine instructions are required"))
+
+		return result.ErrorOrNil()
 	}
 
 	if err := c.ClusterConfig.Validate(); err != nil {
@@ -133,10 +135,6 @@ func (c *Config) Validate(mode config.RuntimeMode, options ...config.ValidationO
 		}
 	}
 
-	if !valid.IsDNSName(c.ClusterConfig.ClusterNetwork.DNSDomain) {
-		result = multierror.Append(result, fmt.Errorf("%q is not a valid DNS name", c.ClusterConfig.ClusterNetwork.DNSDomain))
-	}
-
 	for _, label := range []string{constants.EphemeralPartitionLabel, constants.StatePartitionLabel} {
 		encryptionConfig := c.MachineConfig.SystemDiskEncryption().Get(label)
 		if encryptionConfig != nil {
@@ -178,6 +176,10 @@ func (c *ClusterConfig) Validate() error {
 		result = multierror.Append(result, fmt.Errorf("invalid controlplane endpoint: %w", err))
 	}
 
+	if c.ClusterNetwork != nil && !valid.IsDNSName(c.ClusterNetwork.DNSDomain) {
+		result = multierror.Append(result, fmt.Errorf("%q is not a valid DNS name", c.ClusterNetwork.DNSDomain))
+	}
+
 	return result.ErrorOrNil()
 }
 

pkg/machinery/config/types/v1alpha1/v1alpha1_validation_test.go

@@ -0,0 +1,116 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package v1alpha1_test
+
+import (
+	"fmt"
+	"net/url"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/talos-systems/talos/pkg/machinery/config"
+	"github.com/talos-systems/talos/pkg/machinery/config/types/v1alpha1"
+)
+
+type runtimeMode struct {
+	requiresInstall bool
+}
+
+func (m runtimeMode) String() string {
+	return fmt.Sprintf("runtimeMode(%v)", m.requiresInstall)
+}
+
+func (m runtimeMode) RequiresInstall() bool {
+	return m.requiresInstall
+}
+
+func TestValidate(t *testing.T) {
+	endpointURL, err := url.Parse("https://localhost:6443/")
+	require.NoError(t, err)
+
+	for _, test := range []struct {
+		name            string
+		config          *v1alpha1.Config
+		requiresInstall bool
+		expectedError   string
+	}{
+		{
+			name: "NoMachine",
+			config: &v1alpha1.Config{
+				ConfigVersion: "v1alpha1",
+			},
+			expectedError: `1 error occurred:
+	* machine instructions are required
+
+`,
+		},
+		{
+			name: "NoMachineInstall",
+			config: &v1alpha1.Config{
+				ConfigVersion: "v1alpha1",
+				MachineConfig: &v1alpha1.MachineConfig{},
+				ClusterConfig: &v1alpha1.ClusterConfig{
+					ControlPlane: &v1alpha1.ControlPlaneConfig{
+						Endpoint: &v1alpha1.Endpoint{
+							endpointURL,
+						},
+					},
+				},
+			},
+		},
+		{
+			name: "NoMachineInstallRequired",
+			config: &v1alpha1.Config{
+				ConfigVersion: "v1alpha1",
+				MachineConfig: &v1alpha1.MachineConfig{},
+				ClusterConfig: &v1alpha1.ClusterConfig{
+					ControlPlane: &v1alpha1.ControlPlaneConfig{
+						Endpoint: &v1alpha1.Endpoint{
+							endpointURL,
+						},
+					},
+				},
+			},
+			requiresInstall: true,
+			expectedError: `1 error occurred:
+	* install instructions are required in "runtimeMode(true)" mode
+
+`,
+		},
+		{
+			name: "MachineInstallDisk",
+			config: &v1alpha1.Config{
+				ConfigVersion: "v1alpha1",
+				MachineConfig: &v1alpha1.MachineConfig{
+					MachineInstall: &v1alpha1.InstallConfig{
+						InstallDisk: "/dev/vda",
+					},
+				},
+				ClusterConfig: &v1alpha1.ClusterConfig{
+					ControlPlane: &v1alpha1.ControlPlaneConfig{
+						Endpoint: &v1alpha1.Endpoint{
+							endpointURL,
+						},
+					},
+				},
+			},
+			requiresInstall: true,
+		},
+	} {
+		test := test
+
+		t.Run(test.name, func(t *testing.T) {
+			err := test.config.Validate(runtimeMode{test.requiresInstall}, config.WithLocal())
+
+			if test.expectedError == "" {
+				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, test.expectedError)
+			}
+		})
+	}
+}