Document mocking capabilities for v4 Helm Chart

[blampe]

Users were previously able to inject resources into a v3 Helm Chart via the Call method, but the v4 Chart no longer invokes this client-side.

Let's put together an example of how to mock the v4 Chart resource.

[blampe]

If this works for the customer we can update docs to reflect it.

❯ cat main.go
package main

import (
	helmv4 "github.com/pulumi/pulumi-kubernetes/sdk/v4/go/kubernetes/helm/v4"
	"github.com/pulumi/pulumi/sdk/v3/go/pulumi"
)

func createChart(ctx *pulumi.Context) (*helmv4.Chart, error) {
	return helmv4.NewChart(ctx, "nginx", &helmv4.ChartArgs{
		Chart:   pulumi.String("oci://registry-1.docker.io/bitnamicharts/nginx"),
		Version: pulumi.String("16.0.7"),
	})
}

func main() {
	pulumi.Run(func(ctx *pulumi.Context) error {
		chart, err := createChart(ctx)
		if err != nil {
			return err
		}
		ctx.Export("resources", chart.Resources)
		return nil
	})
}

❯ cat main_test.go
package main

import (
	"fmt"
	"testing"

	"github.com/pulumi/pulumi/sdk/v3/go/common/resource"
	"github.com/pulumi/pulumi/sdk/v3/go/pulumi"
	"github.com/stretchr/testify/assert"
)

type HelmMocks []map[string]interface{}

func (m HelmMocks) NewResource(args pulumi.MockResourceArgs) (string, resource.PropertyMap, error) {
	// Copy our inputs.
	outputs := args.Inputs

	// Convert our map into a PropertyValue Pulumi understands.
	values := []resource.PropertyValue{}
	for _, v := range m {
		values = append(values, resource.NewObjectProperty(resource.NewPropertyMapFromMap(v)))
	}

	// Add our resources to the chart's output.
	outputs["resources"] = resource.NewArrayProperty(values)

	return args.Name + "_id", outputs, nil
}

func (HelmMocks) Call(args pulumi.MockCallArgs) (resource.PropertyMap, error) {
	return nil, fmt.Errorf("not implemented")
}

func TestHelm(t *testing.T) {

	mockResources := []map[string]any{
		{"foo": "bar"},
	}

	pulumi.Run(
		func(ctx *pulumi.Context) error {
			chart, err := createChart(ctx)
			if err != nil {
				return err
			}

			pulumi.All(chart.Resources).ApplyT(func(all []any) error {
				resources := all[0].([]any)

				assert.Len(t, resources, 1)
				return nil
			})

			return nil

		},
		pulumi.WithMocks("project", "stack", HelmMocks(mockResources)),
	)
}