Serialize dynamic value for `bundle validate` output (#1499)

## Changes
Using dynamic values allows us to retain references like
`${resources.jobs...}` even when the type of field is not integer, eg:
`run_job_task`, or in general values that do not map to the Go types for
a field.

## Tests
Integration test

bundle/config/root.go

@@ -471,3 +471,9 @@ func (r Root) GetLocation(path string) dyn.Location {
 	}
 	return v.Location()
 }
+
+// Value returns the dynamic configuration value of the root object. This value
+// is the source of truth and is kept in sync with values in the typed configuration.
+func (r Root) Value() dyn.Value {
+	return r.value
+}

cmd/bundle/validate.go

@@ -119,7 +119,7 @@ func renderTextOutput(cmd *cobra.Command, b *bundle.Bundle, diags diag.Diagnosti
 }
 
 func renderJsonOutput(cmd *cobra.Command, b *bundle.Bundle, diags diag.Diagnostics) error {
-	buf, err := json.MarshalIndent(b.Config, "", "  ")
+	buf, err := json.MarshalIndent(b.Config.Value().AsAny(), "", "  ")
 	if err != nil {
 		return err
 	}

internal/bundle/helpers.go

@@ -51,6 +51,13 @@ func writeConfigFile(t *testing.T, config map[string]any) (string, error) {
 	return filepath, err
 }
 
+func validateBundle(t *testing.T, ctx context.Context, path string) ([]byte, error) {
+	t.Setenv("BUNDLE_ROOT", path)
+	c := internal.NewCobraTestRunnerWithContext(t, ctx, "bundle", "validate", "--output", "json")
+	stdout, _, err := c.Run()
+	return stdout.Bytes(), err
+}
+
 func deployBundle(t *testing.T, ctx context.Context, path string) error {
 	t.Setenv("BUNDLE_ROOT", path)
 	c := internal.NewCobraTestRunnerWithContext(t, ctx, "bundle", "deploy", "--force-lock")

internal/bundle/validate_test.go

@@ -0,0 +1,60 @@
+package bundle
+
+import (
+	"context"
+	"encoding/json"
+	"testing"
+
+	"github.com/databricks/cli/internal/testutil"
+	"github.com/databricks/cli/libs/dyn"
+	"github.com/databricks/cli/libs/dyn/convert"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestAccBundleValidate(t *testing.T) {
+	testutil.GetEnvOrSkipTest(t, "CLOUD_ENV")
+
+	tmpDir := t.TempDir()
+	testutil.WriteFile(t,
+		`
+bundle:
+  name: "foobar"
+
+resources:
+  jobs:
+    outer_loop:
+      name: outer loop
+      tasks:
+        - task_key: my task
+          run_job_task:
+            job_id: ${resources.jobs.inner_loop.id}
+
+    inner_loop:
+      name: inner loop
+
+`, tmpDir, "databricks.yml")
+
+	ctx := context.Background()
+	stdout, err := validateBundle(t, ctx, tmpDir)
+	require.NoError(t, err)
+
+	config := make(map[string]any)
+	err = json.Unmarshal(stdout, &config)
+	require.NoError(t, err)
+
+	getValue := func(key string) any {
+		v, err := convert.FromTyped(config, dyn.NilValue)
+		require.NoError(t, err)
+		v, err = dyn.GetByPath(v, dyn.MustPathFromString(key))
+		require.NoError(t, err)
+		return v.AsAny()
+	}
+
+	assert.Equal(t, "foobar", getValue("bundle.name"))
+	assert.Equal(t, "outer loop", getValue("resources.jobs.outer_loop.name"))
+	assert.Equal(t, "inner loop", getValue("resources.jobs.inner_loop.name"))
+	assert.Equal(t, "my task", getValue("resources.jobs.outer_loop.tasks[0].task_key"))
+	// Assert resource references are retained in the output.
+	assert.Equal(t, "${resources.jobs.inner_loop.id}", getValue("resources.jobs.outer_loop.tasks[0].run_job_task.job_id"))
+}

internal/testutil/file.go

@@ -0,0 +1,48 @@
+package testutil
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TouchNotebook(t *testing.T, elems ...string) string {
+	path := filepath.Join(elems...)
+	err := os.MkdirAll(filepath.Dir(path), 0755)
+	require.NoError(t, err)
+
+	err = os.WriteFile(path, []byte("# Databricks notebook source"), 0644)
+	require.NoError(t, err)
+	return path
+}
+
+func Touch(t *testing.T, elems ...string) string {
+	path := filepath.Join(elems...)
+	err := os.MkdirAll(filepath.Dir(path), 0755)
+	require.NoError(t, err)
+
+	f, err := os.Create(path)
+	require.NoError(t, err)
+
+	err = f.Close()
+	require.NoError(t, err)
+	return path
+}
+
+func WriteFile(t *testing.T, content string, elems ...string) string {
+	path := filepath.Join(elems...)
+	err := os.MkdirAll(filepath.Dir(path), 0755)
+	require.NoError(t, err)
+
+	f, err := os.Create(path)
+	require.NoError(t, err)
+
+	_, err = f.WriteString(content)
+	require.NoError(t, err)
+
+	err = f.Close()
+	require.NoError(t, err)
+	return path
+}

internal/testutil/touch.go

@@ -1,26 +0,0 @@
-package testutil
-
-import (
-	"os"
-	"path/filepath"
-	"testing"
-
-	"github.com/stretchr/testify/require"
-)
-
-func TouchNotebook(t *testing.T, elems ...string) string {
-	path := filepath.Join(elems...)
-	os.MkdirAll(filepath.Dir(path), 0755)
-	err := os.WriteFile(path, []byte("# Databricks notebook source"), 0644)
-	require.NoError(t, err)
-	return path
-}
-
-func Touch(t *testing.T, elems ...string) string {
-	path := filepath.Join(elems...)
-	os.MkdirAll(filepath.Dir(path), 0755)
-	f, err := os.Create(path)
-	require.NoError(t, err)
-	f.Close()
-	return path
-}