Return early in bundle destroy if no deployment exists (#1581)

## Changes
This PR:
1. Moves the if mutator to the bundle package, to live with all-time
greats such as `bundle.Seq` and `bundle.Defer`. Also adds unit tests.
2. `bundle destroy` now returns early if `root_path` does not exist. We
do this by leveraging a `bundle.If` condition.

## Tests
Unit tests and manually.

Here's an example of what it'll look like once the bundle is destroyed.

```
➜  bundle-playground git:(master) ✗ cli bundle destroy
No active deployment found to destroy!
```

I would have added some e2e coverage for this as well, but the
`cobraTestRunner.Run()` method does not seem to return stdout/stderr
logs correctly. We can probably punt looking into it.

bundle/config/mutator/if.go

@@ -1,36 +0,0 @@
-package mutator
-
-import (
-	"context"
-
-	"github.com/databricks/cli/bundle"
-	"github.com/databricks/cli/libs/diag"
-)
-
-type ifMutator struct {
-	condition      func(*bundle.Bundle) bool
-	onTrueMutator  bundle.Mutator
-	onFalseMutator bundle.Mutator
-}
-
-func If(
-	condition func(*bundle.Bundle) bool,
-	onTrueMutator bundle.Mutator,
-	onFalseMutator bundle.Mutator,
-) bundle.Mutator {
-	return &ifMutator{
-		condition, onTrueMutator, onFalseMutator,
-	}
-}
-
-func (m *ifMutator) Apply(ctx context.Context, b *bundle.Bundle) diag.Diagnostics {
-	if m.condition(b) {
-		return bundle.Apply(ctx, b, m.onTrueMutator)
-	} else {
-		return bundle.Apply(ctx, b, m.onFalseMutator)
-	}
-}
-
-func (m *ifMutator) Name() string {
-	return "If"
-}

bundle/if.go

@@ -0,0 +1,40 @@
+package bundle
+
+import (
+	"context"
+
+	"github.com/databricks/cli/libs/diag"
+)
+
+type ifMutator struct {
+	condition      func(context.Context, *Bundle) (bool, error)
+	onTrueMutator  Mutator
+	onFalseMutator Mutator
+}
+
+func If(
+	condition func(context.Context, *Bundle) (bool, error),
+	onTrueMutator Mutator,
+	onFalseMutator Mutator,
+) Mutator {
+	return &ifMutator{
+		condition, onTrueMutator, onFalseMutator,
+	}
+}
+
+func (m *ifMutator) Apply(ctx context.Context, b *Bundle) diag.Diagnostics {
+	v, err := m.condition(ctx, b)
+	if err != nil {
+		return diag.FromErr(err)
+	}
+
+	if v {
+		return Apply(ctx, b, m.onTrueMutator)
+	} else {
+		return Apply(ctx, b, m.onFalseMutator)
+	}
+}
+
+func (m *ifMutator) Name() string {
+	return "If"
+}

bundle/if_test.go

@@ -0,0 +1,53 @@
+package bundle
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestIfMutatorTrue(t *testing.T) {
+	m1 := &testMutator{}
+	m2 := &testMutator{}
+	ifMutator := If(func(context.Context, *Bundle) (bool, error) {
+		return true, nil
+	}, m1, m2)
+
+	b := &Bundle{}
+	diags := Apply(context.Background(), b, ifMutator)
+	assert.NoError(t, diags.Error())
+
+	assert.Equal(t, 1, m1.applyCalled)
+	assert.Equal(t, 0, m2.applyCalled)
+}
+
+func TestIfMutatorFalse(t *testing.T) {
+	m1 := &testMutator{}
+	m2 := &testMutator{}
+	ifMutator := If(func(context.Context, *Bundle) (bool, error) {
+		return false, nil
+	}, m1, m2)
+
+	b := &Bundle{}
+	diags := Apply(context.Background(), b, ifMutator)
+	assert.NoError(t, diags.Error())
+
+	assert.Equal(t, 0, m1.applyCalled)
+	assert.Equal(t, 1, m2.applyCalled)
+}
+
+func TestIfMutatorError(t *testing.T) {
+	m1 := &testMutator{}
+	m2 := &testMutator{}
+	ifMutator := If(func(context.Context, *Bundle) (bool, error) {
+		return true, assert.AnError
+	}, m1, m2)
+
+	b := &Bundle{}
+	diags := Apply(context.Background(), b, ifMutator)
+	assert.Error(t, diags.Error())
+
+	assert.Equal(t, 0, m1.applyCalled)
+	assert.Equal(t, 0, m2.applyCalled)
+}

bundle/phases/destroy.go

@@ -1,15 +1,33 @@
 package phases
 
 import (
+	"context"
+	"errors"
+	"net/http"
+
 	"github.com/databricks/cli/bundle"
 	"github.com/databricks/cli/bundle/deploy/files"
 	"github.com/databricks/cli/bundle/deploy/lock"
 	"github.com/databricks/cli/bundle/deploy/terraform"
+	"github.com/databricks/cli/libs/log"
+	"github.com/databricks/databricks-sdk-go/apierr"
 )
 
+func assertRootPathExists(ctx context.Context, b *bundle.Bundle) (bool, error) {
+	w := b.WorkspaceClient()
+	_, err := w.Workspace.GetStatusByPath(ctx, b.Config.Workspace.RootPath)
+
+	var aerr *apierr.APIError
+	if errors.As(err, &aerr) && aerr.StatusCode == http.StatusNotFound {
+		log.Infof(ctx, "Root path does not exist: %s", b.Config.Workspace.RootPath)
+		return false, nil
+	}
+
+	return true, err
+}
+
 // The destroy phase deletes artifacts and resources.
 func Destroy() bundle.Mutator {
-
 	destroyMutator := bundle.Seq(
 		lock.Acquire(),
 		bundle.Defer(
@@ -29,6 +47,13 @@ func Destroy() bundle.Mutator {
 
 	return newPhase(
 		"destroy",
-		[]bundle.Mutator{destroyMutator},
+		[]bundle.Mutator{
+			// Only run deploy mutator if root path exists.
+			bundle.If(
+				assertRootPathExists,
+				destroyMutator,
+				bundle.LogString("No active deployment found to destroy!"),
+			),
+		},
 	)
 }

bundle/python/transform.go

@@ -1,6 +1,7 @@
 package python
 
 import (
+	"context"
 	"fmt"
 	"strconv"
 	"strings"
@@ -63,9 +64,10 @@ dbutils.notebook.exit(s)
 // which installs uploaded wheels using %pip and then calling corresponding
 // entry point.
 func TransformWheelTask() bundle.Mutator {
-	return mutator.If(
+	return bundle.If(
-		func(b *bundle.Bundle) bool {
+		func(_ context.Context, b *bundle.Bundle) (bool, error) {
-			return b.Config.Experimental != nil && b.Config.Experimental.PythonWheelWrapper
+			res := b.Config.Experimental != nil && b.Config.Experimental.PythonWheelWrapper
+			return res, nil
 		},
 		mutator.NewTrampoline(
 			"python_wheel",