Support lookup by name of notification destinations (#1922)

## Changes

Add support for notification destinations in variable lookups.

More information:
https://docs.databricks.com/en/admin/workspace-settings/notification-destinations.html

Depends on #1921.

## Tests

* New unit test
* Manually confirmed that the lookup works

bundle/config/variable/lookup.go

@@ -22,6 +22,8 @@ type Lookup struct {
 
 	Metastore string `json:"metastore,omitempty"`
 
+	NotificationDestination string `json:"notification_destination,omitempty"`
+
 	Pipeline string `json:"pipeline,omitempty"`
 
 	Query string `json:"query,omitempty"`
@@ -63,6 +65,9 @@ func (l *Lookup) constructResolver() (resolver, error) {
 	if l.Metastore != "" {
 		resolvers = append(resolvers, resolveMetastore{name: l.Metastore})
 	}
+	if l.NotificationDestination != "" {
+		resolvers = append(resolvers, resolveNotificationDestination{name: l.NotificationDestination})
+	}
 	if l.Pipeline != "" {
 		resolvers = append(resolvers, resolvePipeline{name: l.Pipeline})
 	}

bundle/config/variable/resolve_notification_destination.go

@@ -0,0 +1,46 @@
+package variable
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/databricks/databricks-sdk-go"
+	"github.com/databricks/databricks-sdk-go/service/settings"
+)
+
+type resolveNotificationDestination struct {
+	name string
+}
+
+func (l resolveNotificationDestination) Resolve(ctx context.Context, w *databricks.WorkspaceClient) (string, error) {
+	result, err := w.NotificationDestinations.ListAll(ctx, settings.ListNotificationDestinationsRequest{
+		// The default page size for this API is 20.
+		// We use a higher value to make fewer API calls.
+		PageSize: 200,
+	})
+	if err != nil {
+		return "", err
+	}
+
+	// Collect all notification destinations with the given name.
+	var entities []settings.ListNotificationDestinationsResult
+	for _, entity := range result {
+		if entity.DisplayName == l.name {
+			entities = append(entities, entity)
+		}
+	}
+
+	// Return the ID of the first matching notification destination.
+	switch len(entities) {
+	case 0:
+		return "", fmt.Errorf("notification destination named %q does not exist", l.name)
+	case 1:
+		return entities[0].Id, nil
+	default:
+		return "", fmt.Errorf("there are %d instances of clusters named %q", len(entities), l.name)
+	}
+}
+
+func (l resolveNotificationDestination) String() string {
+	return fmt.Sprintf("notification-destination: %s", l.name)
+}

bundle/config/variable/resolve_notification_destination_test.go

@@ -0,0 +1,82 @@
+package variable
+
+import (
+	"context"
+	"fmt"
+	"testing"
+
+	"github.com/databricks/databricks-sdk-go/experimental/mocks"
+	"github.com/databricks/databricks-sdk-go/service/settings"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
+)
+
+func TestResolveNotificationDestination_ResolveSuccess(t *testing.T) {
+	m := mocks.NewMockWorkspaceClient(t)
+
+	api := m.GetMockNotificationDestinationsAPI()
+	api.EXPECT().
+		ListAll(mock.Anything, mock.Anything).
+		Return([]settings.ListNotificationDestinationsResult{
+			{Id: "1234", DisplayName: "destination"},
+		}, nil)
+
+	ctx := context.Background()
+	l := resolveNotificationDestination{name: "destination"}
+	result, err := l.Resolve(ctx, m.WorkspaceClient)
+	require.NoError(t, err)
+	assert.Equal(t, "1234", result)
+}
+
+func TestResolveNotificationDestination_ResolveError(t *testing.T) {
+	m := mocks.NewMockWorkspaceClient(t)
+
+	api := m.GetMockNotificationDestinationsAPI()
+	api.EXPECT().
+		ListAll(mock.Anything, mock.Anything).
+		Return(nil, fmt.Errorf("bad"))
+
+	ctx := context.Background()
+	l := resolveNotificationDestination{name: "destination"}
+	_, err := l.Resolve(ctx, m.WorkspaceClient)
+	assert.ErrorContains(t, err, "bad")
+}
+
+func TestResolveNotificationDestination_ResolveNotFound(t *testing.T) {
+	m := mocks.NewMockWorkspaceClient(t)
+
+	api := m.GetMockNotificationDestinationsAPI()
+	api.EXPECT().
+		ListAll(mock.Anything, mock.Anything).
+		Return([]settings.ListNotificationDestinationsResult{}, nil)
+
+	ctx := context.Background()
+	l := resolveNotificationDestination{name: "destination"}
+	_, err := l.Resolve(ctx, m.WorkspaceClient)
+	require.Error(t, err)
+	assert.ErrorContains(t, err, `notification destination named "destination" does not exist`)
+}
+
+func TestResolveNotificationDestination_ResolveMultiple(t *testing.T) {
+	m := mocks.NewMockWorkspaceClient(t)
+
+	api := m.GetMockNotificationDestinationsAPI()
+	api.EXPECT().
+		ListAll(mock.Anything, mock.Anything).
+		Return([]settings.ListNotificationDestinationsResult{
+			{Id: "1234", DisplayName: "destination"},
+			{Id: "5678", DisplayName: "destination"},
+		}, nil)
+
+	ctx := context.Background()
+	l := resolveNotificationDestination{name: "destination"}
+	_, err := l.Resolve(ctx, m.WorkspaceClient)
+	require.Error(t, err)
+	assert.ErrorContains(t, err, `there are 2 instances of clusters named "destination"`)
+}
+
+func TestResolveNotificationDestination_String(t *testing.T) {
+	l := resolveNotificationDestination{name: "name"}
+	assert.Equal(t, "notification-destination: name", l.String())
+}