Merge 96a6cef0d6 into 7d732ceba8

## Changes

We had a number of copies of test helpers for `io/fs` in the repository.

This change consolidates all of them to use the `libs/fakefs` package.

## Tests

Unit tests pass.

bundle/config/experimental.go

@@ -45,6 +45,12 @@ type PyDABs struct {
 	// These packages are imported to discover resources, resource generators, and mutators.
 	// This list can include namespace packages, which causes the import of nested packages.
 	Import []string `json:"import,omitempty"`
+
+	// LoadLocations is a flag to enable loading Python source locations from the PyDABs.
+	//
+	// Locations are only supported since PyDABs 0.6.0, and because of that,
+	// this flag is disabled by default.
+	LoadLocations bool `json:"load_locations,omitempty"`
 }
 
 type Command string

bundle/config/mutator/prepend_workspace_prefix.go

@@ -44,6 +44,11 @@ func (m *prependWorkspacePrefix) Apply(ctx context.Context, b *bundle.Bundle) di
 					return dyn.InvalidValue, fmt.Errorf("expected string, got %s", v.Kind())
 				}
 
+				// Skip prefixing if the path does not start with /, it might be variable reference or smth else.
+				if !strings.HasPrefix(path, "/") {
+					return pv, nil
+				}
+
 				for _, prefix := range skipPrefixes {
 					if strings.HasPrefix(path, prefix) {
 						return pv, nil

bundle/config/mutator/prepend_workspace_prefix_test.go

@@ -31,6 +31,14 @@ func TestPrependWorkspacePrefix(t *testing.T) {
 			path:     "/Volumes/Users/test",
 			expected: "/Volumes/Users/test",
 		},
+		{
+			path:     "~/test",
+			expected: "~/test",
+		},
+		{
+			path:     "${workspace.file_path}/test",
+			expected: "${workspace.file_path}/test",
+		},
 	}
 
 	for _, tc := range testCases {

bundle/config/mutator/python/python_diagnostics.go

@@ -9,6 +9,7 @@ import (
 	"github.com/databricks/cli/libs/dyn"
 )
 
+// pythonDiagnostic is a single entry in diagnostics.json
 type pythonDiagnostic struct {
 	Severity pythonSeverity           `json:"severity"`
 	Summary  string                   `json:"summary"`

bundle/config/mutator/python/python_locations.go

@@ -0,0 +1,181 @@
+package python
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"path/filepath"
+
+	"github.com/databricks/cli/libs/dyn"
+)
+
+// generatedFileName is used as the virtual file name for YAML generated by PyDABs.
+//
+// mergePythonLocations replaces dyn.Location with generatedFileName with locations loaded
+// from locations.json
+const generatedFileName = "__generated_by_pydabs__.yml"
+
+// pythonLocations is data structure for efficient location lookup for a given path
+//
+// Locations form a tree, and we assign locations of the closest ancestor to each dyn.Value based on its path.
+// We implement it as a trie (prefix tree) where keys are components of the path. With that, lookups are O(n)
+// where n is the number of components in the path.
+//
+// For example, with locations.json:
+//
+//	{"path": "resources.jobs.job_0", "file": "src/examples/job_0.py", "line": 3, "column": 5}
+//	{"path": "resources.jobs.job_0.tasks[0].task_key", "file": "src/examples/job_0.py", "line": 10, "column": 5}
+//	{"path": "resources.jobs.job_1", "file": "src/examples/job_1.py", "line": 5, "column": 7}
+//
+// - resources.jobs.job_0.tasks[0].task_key is located at job_0.py:10:5
+//
+//   - resources.jobs.job_0.tasks[0].email_notifications is located at job_0.py:3:5,
+//     because we use the location of the job as the most precise approximation.
+type pythonLocations struct {
+	// descendants referenced by index, e.g. '.foo'
+	keys map[string]*pythonLocations
+
+	// descendants referenced by key, e.g. '[0]'
+	indexes map[int]*pythonLocations
+
+	// location for the current node if it exists
+	location dyn.Location
+
+	// if true, location is present
+	exists bool
+}
+
+// pythonLocationEntry is a single entry in locations.json
+type pythonLocationEntry struct {
+	Path   string `json:"path"`
+	File   string `json:"file"`
+	Line   int    `json:"line"`
+	Column int    `json:"column"`
+}
+
+// mergePythonLocations applies locations from Python mutator into given dyn.Value
+//
+// The primary use-case is to merge locations.json with output.json, so that any
+// validation errors will point to Python source code instead of generated YAML.
+func mergePythonLocations(value dyn.Value, locations *pythonLocations) (dyn.Value, error) {
+	return dyn.Walk(value, func(path dyn.Path, value dyn.Value) (dyn.Value, error) {
+		newLocation, ok := findPythonLocation(locations, path)
+		if !ok {
+			return value, nil
+		}
+
+		var newLocations []dyn.Location
+
+		// the first item in the list is the "last" location used for error reporting
+		newLocations = append(newLocations, newLocation)
+
+		for _, location := range value.Locations() {
+			// When loaded, dyn.Value created by PyDABs use the virtual file path as their location,
+			// we replace it with newLocation.
+			if filepath.Base(location.File) == generatedFileName {
+				continue
+			}
+
+			newLocations = append(newLocations, location)
+		}
+
+		return value.WithLocations(newLocations), nil
+	})
+}
+
+// parsePythonLocations parses locations.json from the Python mutator.
+//
+// locations file is newline-separated JSON objects with pythonLocationEntry structure.
+func parsePythonLocations(input io.Reader) (*pythonLocations, error) {
+	decoder := json.NewDecoder(input)
+	locations := newPythonLocations()
+
+	for decoder.More() {
+		var entry pythonLocationEntry
+
+		err := decoder.Decode(&entry)
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse python location: %s", err)
+		}
+
+		path, err := dyn.NewPathFromString(entry.Path)
+		if err != nil {
+			return nil, fmt.Errorf("failed to parse python location: %s", err)
+		}
+
+		location := dyn.Location{
+			File:   entry.File,
+			Line:   entry.Line,
+			Column: entry.Column,
+		}
+
+		putPythonLocation(locations, path, location)
+	}
+
+	return locations, nil
+}
+
+// putPythonLocation puts the location to the trie for the given path
+func putPythonLocation(trie *pythonLocations, path dyn.Path, location dyn.Location) {
+	var currentNode = trie
+
+	for _, component := range path {
+		if key := component.Key(); key != "" {
+			if _, ok := currentNode.keys[key]; !ok {
+				currentNode.keys[key] = newPythonLocations()
+			}
+
+			currentNode = currentNode.keys[key]
+		} else {
+			index := component.Index()
+			if _, ok := currentNode.indexes[index]; !ok {
+				currentNode.indexes[index] = newPythonLocations()
+			}
+
+			currentNode = currentNode.indexes[index]
+		}
+	}
+
+	currentNode.location = location
+	currentNode.exists = true
+}
+
+// newPythonLocations creates a new trie node
+func newPythonLocations() *pythonLocations {
+	return &pythonLocations{
+		keys:    make(map[string]*pythonLocations),
+		indexes: make(map[int]*pythonLocations),
+	}
+}
+
+// findPythonLocation finds the location or closest ancestor location in the trie for the given path
+// if no ancestor or exact location is found, false is returned.
+func findPythonLocation(locations *pythonLocations, path dyn.Path) (dyn.Location, bool) {
+	var currentNode = locations
+	var lastLocation = locations.location
+	var exists = locations.exists
+
+	for _, component := range path {
+		if key := component.Key(); key != "" {
+			if _, ok := currentNode.keys[key]; !ok {
+				break
+			}
+
+			currentNode = currentNode.keys[key]
+		} else {
+			index := component.Index()
+			if _, ok := currentNode.indexes[index]; !ok {
+				break
+			}
+
+			currentNode = currentNode.indexes[index]
+		}
+
+		if currentNode.exists {
+			lastLocation = currentNode.location
+			exists = true
+		}
+	}
+
+	return lastLocation, exists
+}

bundle/config/mutator/python/python_locations_test.go

@@ -0,0 +1,124 @@
+package python
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/databricks/cli/libs/dyn"
+	assert "github.com/databricks/cli/libs/dyn/dynassert"
+)
+
+func TestMergeLocations(t *testing.T) {
+	pythonLocation := dyn.Location{File: "foo.py", Line: 1, Column: 1}
+	generatedLocation := dyn.Location{File: generatedFileName, Line: 1, Column: 1}
+	yamlLocation := dyn.Location{File: "foo.yml", Line: 1, Column: 1}
+
+	locations := newPythonLocations()
+	putPythonLocation(locations, dyn.MustPathFromString("foo"), pythonLocation)
+
+	input := dyn.NewValue(
+		map[string]dyn.Value{
+			"foo": dyn.NewValue(
+				map[string]dyn.Value{
+					"baz": dyn.NewValue("baz", []dyn.Location{yamlLocation}),
+					"qux": dyn.NewValue("baz", []dyn.Location{generatedLocation, yamlLocation}),
+				},
+				[]dyn.Location{},
+			),
+			"bar": dyn.NewValue("baz", []dyn.Location{generatedLocation}),
+		},
+		[]dyn.Location{yamlLocation},
+	)
+
+	expected := dyn.NewValue(
+		map[string]dyn.Value{
+			"foo": dyn.NewValue(
+				map[string]dyn.Value{
+					// pythonLocation is appended to the beginning of the list if absent
+					"baz": dyn.NewValue("baz", []dyn.Location{pythonLocation, yamlLocation}),
+					// generatedLocation is replaced by pythonLocation
+					"qux": dyn.NewValue("baz", []dyn.Location{pythonLocation, yamlLocation}),
+				},
+				[]dyn.Location{pythonLocation},
+			),
+			// if location is unknown, we keep it as-is
+			"bar": dyn.NewValue("baz", []dyn.Location{generatedLocation}),
+		},
+		[]dyn.Location{yamlLocation},
+	)
+
+	actual, err := mergePythonLocations(input, locations)
+
+	assert.NoError(t, err)
+	assert.Equal(t, expected, actual)
+}
+
+func TestFindLocation(t *testing.T) {
+	location0 := dyn.Location{File: "foo.py", Line: 1, Column: 1}
+	location1 := dyn.Location{File: "foo.py", Line: 2, Column: 1}
+
+	locations := newPythonLocations()
+	putPythonLocation(locations, dyn.MustPathFromString("foo"), location0)
+	putPythonLocation(locations, dyn.MustPathFromString("foo.bar"), location1)
+
+	actual, exists := findPythonLocation(locations, dyn.MustPathFromString("foo.bar"))
+
+	assert.True(t, exists)
+	assert.Equal(t, location1, actual)
+}
+
+func TestFindLocation_indexPathComponent(t *testing.T) {
+	location0 := dyn.Location{File: "foo.py", Line: 1, Column: 1}
+	location1 := dyn.Location{File: "foo.py", Line: 2, Column: 1}
+	location2 := dyn.Location{File: "foo.py", Line: 3, Column: 1}
+
+	locations := newPythonLocations()
+	putPythonLocation(locations, dyn.MustPathFromString("foo"), location0)
+	putPythonLocation(locations, dyn.MustPathFromString("foo.bar"), location1)
+	putPythonLocation(locations, dyn.MustPathFromString("foo.bar[0]"), location2)
+
+	actual, exists := findPythonLocation(locations, dyn.MustPathFromString("foo.bar[0]"))
+
+	assert.True(t, exists)
+	assert.Equal(t, location2, actual)
+}
+
+func TestFindLocation_closestAncestorLocation(t *testing.T) {
+	location0 := dyn.Location{File: "foo.py", Line: 1, Column: 1}
+	location1 := dyn.Location{File: "foo.py", Line: 2, Column: 1}
+
+	locations := newPythonLocations()
+	putPythonLocation(locations, dyn.MustPathFromString("foo"), location0)
+	putPythonLocation(locations, dyn.MustPathFromString("foo.bar"), location1)
+
+	actual, exists := findPythonLocation(locations, dyn.MustPathFromString("foo.bar.baz"))
+
+	assert.True(t, exists)
+	assert.Equal(t, location1, actual)
+}
+
+func TestFindLocation_unknownLocation(t *testing.T) {
+	location0 := dyn.Location{File: "foo.py", Line: 1, Column: 1}
+	location1 := dyn.Location{File: "foo.py", Line: 2, Column: 1}
+
+	locations := newPythonLocations()
+	putPythonLocation(locations, dyn.MustPathFromString("foo"), location0)
+	putPythonLocation(locations, dyn.MustPathFromString("foo.bar"), location1)
+
+	_, exists := findPythonLocation(locations, dyn.MustPathFromString("bar"))
+
+	assert.False(t, exists)
+}
+
+func TestParsePythonLocations(t *testing.T) {
+	expected := dyn.Location{File: "foo.py", Line: 1, Column: 2}
+
+	input := `{"path": "foo", "file": "foo.py", "line": 1, "column": 2}`
+	reader := bytes.NewReader([]byte(input))
+	locations, err := parsePythonLocations(reader)
+
+	assert.NoError(t, err)
+
+	assert.True(t, locations.keys["foo"].exists)
+	assert.Equal(t, expected, locations.keys["foo"].location)
+}

bundle/config/mutator/python/python_mutator.go

@@ -7,9 +7,12 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"io/fs"
 	"os"
 	"path/filepath"
 
+	"github.com/databricks/cli/bundle/config/mutator/paths"
+
 	"github.com/databricks/databricks-sdk-go/logger"
 	"github.com/fatih/color"
 
@@ -108,7 +111,12 @@ func (m *pythonMutator) Apply(ctx context.Context, b *bundle.Bundle) diag.Diagno
 			return dyn.InvalidValue, fmt.Errorf("failed to create cache dir: %w", err)
 		}
 
-		rightRoot, diags := m.runPythonMutator(ctx, cacheDir, b.BundleRootPath, pythonPath, leftRoot)
+		rightRoot, diags := m.runPythonMutator(ctx, leftRoot, runPythonMutatorOpts{
+			cacheDir:       cacheDir,
+			bundleRootPath: b.BundleRootPath,
+			pythonPath:     pythonPath,
+			loadLocations:  experimental.PyDABs.LoadLocations,
+		})
 		mutateDiags = diags
 		if diags.HasError() {
 			return dyn.InvalidValue, mutateDiagsHasError
@@ -152,13 +160,21 @@ func createCacheDir(ctx context.Context) (string, error) {
 	return os.MkdirTemp("", "-pydabs")
 }
 
-func (m *pythonMutator) runPythonMutator(ctx context.Context, cacheDir string, rootPath string, pythonPath string, root dyn.Value) (dyn.Value, diag.Diagnostics) {
-	inputPath := filepath.Join(cacheDir, "input.json")
-	outputPath := filepath.Join(cacheDir, "output.json")
-	diagnosticsPath := filepath.Join(cacheDir, "diagnostics.json")
+type runPythonMutatorOpts struct {
+	cacheDir       string
+	bundleRootPath string
+	pythonPath     string
+	loadLocations  bool
+}
+
+func (m *pythonMutator) runPythonMutator(ctx context.Context, root dyn.Value, opts runPythonMutatorOpts) (dyn.Value, diag.Diagnostics) {
+	inputPath := filepath.Join(opts.cacheDir, "input.json")
+	outputPath := filepath.Join(opts.cacheDir, "output.json")
+	diagnosticsPath := filepath.Join(opts.cacheDir, "diagnostics.json")
+	locationsPath := filepath.Join(opts.cacheDir, "locations.json")
 
 	args := []string{
-		pythonPath,
+		opts.pythonPath,
 		"-m",
 		"databricks.bundles.build",
 		"--phase",
@@ -171,6 +187,10 @@ func (m *pythonMutator) runPythonMutator(ctx context.Context, cacheDir string, r
 		diagnosticsPath,
 	}
 
+	if opts.loadLocations {
+		args = append(args, "--locations", locationsPath)
+	}
+
 	if err := writeInputFile(inputPath, root); err != nil {
 		return dyn.InvalidValue, diag.Errorf("failed to write input file: %s", err)
 	}
@@ -185,7 +205,7 @@ func (m *pythonMutator) runPythonMutator(ctx context.Context, cacheDir string, r
 	_, processErr := process.Background(
 		ctx,
 		args,
-		process.WithDir(rootPath),
+		process.WithDir(opts.bundleRootPath),
 		process.WithStderrWriter(stderrWriter),
 		process.WithStdoutWriter(stdoutWriter),
 	)
@@ -221,7 +241,12 @@ func (m *pythonMutator) runPythonMutator(ctx context.Context, cacheDir string, r
 		return dyn.InvalidValue, diag.Errorf("failed to load diagnostics: %s", pythonDiagnosticsErr)
 	}
 
-	output, outputDiags := loadOutputFile(rootPath, outputPath)
+	locations, err := loadLocationsFile(locationsPath)
+	if err != nil {
+		return dyn.InvalidValue, diag.Errorf("failed to load locations: %s", err)
+	}
+
+	output, outputDiags := loadOutputFile(opts.bundleRootPath, outputPath, locations)
 	pythonDiagnostics = pythonDiagnostics.Extend(outputDiags)
 
 	// we pass through pythonDiagnostic because it contains warnings
@@ -266,7 +291,21 @@ func writeInputFile(inputPath string, input dyn.Value) error {
 	return os.WriteFile(inputPath, rootConfigJson, 0600)
 }
 
-func loadOutputFile(rootPath string, outputPath string) (dyn.Value, diag.Diagnostics) {
+// loadLocationsFile loads locations.json containing source locations for generated YAML.
+func loadLocationsFile(locationsPath string) (*pythonLocations, error) {
+	locationsFile, err := os.Open(locationsPath)
+	if errors.Is(err, fs.ErrNotExist) {
+		return newPythonLocations(), nil
+	} else if err != nil {
+		return nil, fmt.Errorf("failed to open locations file: %w", err)
+	}
+
+	defer locationsFile.Close()
+
+	return parsePythonLocations(locationsFile)
+}
+
+func loadOutputFile(rootPath string, outputPath string, locations *pythonLocations) (dyn.Value, diag.Diagnostics) {
 	outputFile, err := os.Open(outputPath)
 	if err != nil {
 		return dyn.InvalidValue, diag.FromErr(fmt.Errorf("failed to open output file: %w", err))
@@ -277,12 +316,12 @@ func loadOutputFile(rootPath string, outputPath string) (dyn.Value, diag.Diagnos
 	// we need absolute path because later parts of pipeline assume all paths are absolute
 	// and this file will be used as location to resolve relative paths.
 	//
-	// virtualPath has to stay in rootPath, because locations outside root path are not allowed:
+	// virtualPath has to stay in bundleRootPath, because locations outside root path are not allowed:
 	//
 	//   Error: path /var/folders/.../pydabs/dist/*.whl is not contained in bundle root path
 	//
 	// for that, we pass virtualPath instead of outputPath as file location
-	virtualPath, err := filepath.Abs(filepath.Join(rootPath, "__generated_by_pydabs__.yml"))
+	virtualPath, err := filepath.Abs(filepath.Join(rootPath, generatedFileName))
 	if err != nil {
 		return dyn.InvalidValue, diag.FromErr(fmt.Errorf("failed to get absolute path: %w", err))
 	}
@@ -292,7 +331,25 @@ func loadOutputFile(rootPath string, outputPath string) (dyn.Value, diag.Diagnos
 		return dyn.InvalidValue, diag.FromErr(fmt.Errorf("failed to parse output file: %w", err))
 	}
 
-	return strictNormalize(config.Root{}, generated)
+	// paths are resolved relative to locations of their values, if we change location
+	// we have to update each path, until we simplify that, we don't update locations
+	// for such values, so we don't change how paths are resolved
+	_, err = paths.VisitJobPaths(generated, func(p dyn.Path, kind paths.PathKind, v dyn.Value) (dyn.Value, error) {
+		putPythonLocation(locations, p, v.Location())
+		return v, nil
+	})
+	if err != nil {
+		return dyn.InvalidValue, diag.FromErr(fmt.Errorf("failed to update locations: %w", err))
+	}
+
+	// generated has dyn.Location as if it comes from generated YAML file
+	// earlier we loaded locations.json with source locations in Python code
+	generatedWithLocations, err := mergePythonLocations(generated, locations)
+	if err != nil {
+		return dyn.InvalidValue, diag.FromErr(fmt.Errorf("failed to update locations: %w", err))
+	}
+
+	return strictNormalize(config.Root{}, generatedWithLocations)
 }
 
 func strictNormalize(dst any, generated dyn.Value) (dyn.Value, diag.Diagnostics) {

bundle/config/mutator/python/python_mutator_test.go

@@ -6,7 +6,6 @@ import (
 	"os"
 	"os/exec"
 	"path/filepath"
-	"reflect"
 	"runtime"
 	"testing"
 
@@ -47,6 +46,7 @@ func TestPythonMutator_load(t *testing.T) {
         pydabs:
           enabled: true
           venv_path: .venv
+          load_locations: true
       resources:
         jobs:
           job0:
@@ -65,7 +65,8 @@ func TestPythonMutator_load(t *testing.T) {
 			"experimental": {
 				"pydabs": {
 					"enabled": true,
-					"venv_path": ".venv"
+					"venv_path": ".venv",
+					"load_locations": true
 				}
 			},
 			"resources": {
@@ -80,6 +81,8 @@ func TestPythonMutator_load(t *testing.T) {
 			}
 		}`,
 		`{"severity": "warning", "summary": "job doesn't have any tasks", "location": {"file": "src/examples/file.py", "line": 10, "column": 5}}`,
+		`{"path": "resources.jobs.job0", "file": "src/examples/job0.py", "line": 3, "column": 5}
+		{"path": "resources.jobs.job1", "file": "src/examples/job1.py", "line": 5, "column": 7}`,
 	)
 
 	mutator := PythonMutator(PythonMutatorPhaseLoad)
@@ -97,6 +100,25 @@ func TestPythonMutator_load(t *testing.T) {
 		assert.Equal(t, "job_1", job1.Name)
 	}
 
+	// output of locations.json should be applied to underlying dyn.Value
+	err := b.Config.Mutate(func(v dyn.Value) (dyn.Value, error) {
+		name1, err := dyn.GetByPath(v, dyn.MustPathFromString("resources.jobs.job1.name"))
+		if err != nil {
+			return dyn.InvalidValue, err
+		}
+
+		assert.Equal(t, []dyn.Location{
+			{
+				File:   "src/examples/job1.py",
+				Line:   5,
+				Column: 7,
+			},
+		}, name1.Locations())
+
+		return v, nil
+	})
+	assert.NoError(t, err)
+
 	assert.Equal(t, 1, len(diags))
 	assert.Equal(t, "job doesn't have any tasks", diags[0].Summary)
 	assert.Equal(t, []dyn.Location{
@@ -106,7 +128,6 @@ func TestPythonMutator_load(t *testing.T) {
 			Column: 5,
 		},
 	}, diags[0].Locations)
-
 }
 
 func TestPythonMutator_load_disallowed(t *testing.T) {
@@ -146,7 +167,7 @@ func TestPythonMutator_load_disallowed(t *testing.T) {
 					}
 				}
 			}
-		}`, "")
+		}`, "", "")
 
 	mutator := PythonMutator(PythonMutatorPhaseLoad)
 	diag := bundle.Apply(ctx, b, mutator)
@@ -191,7 +212,7 @@ func TestPythonMutator_init(t *testing.T) {
 					}
 				}
 			}
-		}`, "")
+		}`, "", "")
 
 	mutator := PythonMutator(PythonMutatorPhaseInit)
 	diag := bundle.Apply(ctx, b, mutator)
@@ -252,7 +273,7 @@ func TestPythonMutator_badOutput(t *testing.T) {
 					}
 				}
 			}
-		}`, "")
+		}`, "", "")
 
 	mutator := PythonMutator(PythonMutatorPhaseLoad)
 	diag := bundle.Apply(ctx, b, mutator)
@@ -588,7 +609,7 @@ or activate the environment before running CLI commands:
 	assert.Equal(t, expected, out)
 }
 
-func withProcessStub(t *testing.T, args []string, output string, diagnostics string) context.Context {
+func withProcessStub(t *testing.T, args []string, output string, diagnostics string, locations string) context.Context {
 	ctx := context.Background()
 	ctx, stub := process.WithStub(ctx)
 
@@ -600,32 +621,51 @@ func withProcessStub(t *testing.T, args []string, output string, diagnostics str
 
 	inputPath := filepath.Join(cacheDir, "input.json")
 	outputPath := filepath.Join(cacheDir, "output.json")
+	locationsPath := filepath.Join(cacheDir, "locations.json")
 	diagnosticsPath := filepath.Join(cacheDir, "diagnostics.json")
 
-	args = append(args, "--input", inputPath)
-	args = append(args, "--output", outputPath)
-	args = append(args, "--diagnostics", diagnosticsPath)
-
 	stub.WithCallback(func(actual *exec.Cmd) error {
 		_, err := os.Stat(inputPath)
 		assert.NoError(t, err)
 
-		if reflect.DeepEqual(actual.Args, args) {
-			err := os.WriteFile(outputPath, []byte(output), 0600)
-			require.NoError(t, err)
+		actualInputPath := getArg(actual.Args, "--input")
+		actualOutputPath := getArg(actual.Args, "--output")
+		actualDiagnosticsPath := getArg(actual.Args, "--diagnostics")
+		actualLocationsPath := getArg(actual.Args, "--locations")
 
-			err = os.WriteFile(diagnosticsPath, []byte(diagnostics), 0600)
-			require.NoError(t, err)
+		require.Equal(t, inputPath, actualInputPath)
+		require.Equal(t, outputPath, actualOutputPath)
+		require.Equal(t, diagnosticsPath, actualDiagnosticsPath)
 
-			return nil
-		} else {
-			return fmt.Errorf("unexpected command: %v", actual.Args)
+		// locations is an optional argument
+		if locations != "" {
+			require.Equal(t, locationsPath, actualLocationsPath)
+
+			err = os.WriteFile(locationsPath, []byte(locations), 0600)
+			require.NoError(t, err)
 		}
+
+		err = os.WriteFile(outputPath, []byte(output), 0600)
+		require.NoError(t, err)
+
+		err = os.WriteFile(diagnosticsPath, []byte(diagnostics), 0600)
+		require.NoError(t, err)
+
+		return nil
 	})
 
 	return ctx
 }
 
+func getArg(args []string, name string) string {
+	for i := 0; i < len(args); i++ {
+		if args[i] == name {
+			return args[i+1]
+		}
+	}
+	return ""
+}
+
 func loadYaml(name string, content string) *bundle.Bundle {
 	v, diag := config.LoadFromBytes(name, []byte(content))
 

cmd/fs/helpers_test.go

@@ -7,6 +7,7 @@ import (
 	"testing"
 
 	"github.com/databricks/cli/cmd/root"
+	"github.com/databricks/cli/libs/fakefs"
 	"github.com/databricks/cli/libs/filer"
 	"github.com/databricks/databricks-sdk-go/experimental/mocks"
 	"github.com/spf13/cobra"
@@ -84,7 +85,7 @@ func setupTest(t *testing.T) (*validArgs, *cobra.Command, *mocks.MockWorkspaceCl
 	cmd, m := setupCommand(t)
 
 	fakeFilerForPath := func(ctx context.Context, fullPath string) (filer.Filer, string, error) {
-		fakeFiler := filer.NewFakeFiler(map[string]filer.FakeFileInfo{
+		fakeFiler := filer.NewFakeFiler(map[string]fakefs.FileInfo{
 			"dir":       {FakeName: "root", FakeDir: true},
 			"dir/dirA":  {FakeDir: true},
 			"dir/dirB":  {FakeDir: true},

libs/fakefs/fakefs.go

@@ -1,18 +1,21 @@
 package fakefs
 
 import (
+	"fmt"
 	"io/fs"
 	"time"
 )
 
+var ErrNotImplemented = fmt.Errorf("not implemented")
+
 // DirEntry is a fake implementation of [fs.DirEntry].
 type DirEntry struct {
-	FileInfo
+	fs.FileInfo
 }
 
 func (entry DirEntry) Type() fs.FileMode {
 	typ := fs.ModePerm
-	if entry.FakeDir {
+	if entry.IsDir() {
 		typ |= fs.ModeDir
 	}
 	return typ
@@ -53,3 +56,32 @@ func (info FileInfo) IsDir() bool {
 func (info FileInfo) Sys() any {
 	return nil
 }
+
+// File is a fake implementation of [fs.File].
+type File struct {
+	FileInfo fs.FileInfo
+}
+
+func (f File) Close() error {
+	return nil
+}
+
+func (f File) Read(p []byte) (n int, err error) {
+	return 0, ErrNotImplemented
+}
+
+func (f File) Stat() (fs.FileInfo, error) {
+	return f.FileInfo, nil
+}
+
+// FS is a fake implementation of [fs.FS].
+type FS map[string]fs.File
+
+func (f FS) Open(name string) (fs.File, error) {
+	e, ok := f[name]
+	if !ok {
+		return nil, fs.ErrNotExist
+	}
+
+	return e, nil
+}

libs/fakefs/fakefs_test.go

@@ -0,0 +1,38 @@
+package fakefs
+
+import (
+	"io/fs"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestFile(t *testing.T) {
+	var fakefile fs.File = File{
+		FileInfo: FileInfo{
+			FakeName: "file",
+		},
+	}
+
+	_, err := fakefile.Read([]byte{})
+	assert.ErrorIs(t, err, ErrNotImplemented)
+
+	fi, err := fakefile.Stat()
+	assert.NoError(t, err)
+	assert.Equal(t, "file", fi.Name())
+
+	err = fakefile.Close()
+	assert.NoError(t, err)
+}
+
+func TestFS(t *testing.T) {
+	var fakefs fs.FS = FS{
+		"file": File{},
+	}
+
+	_, err := fakefs.Open("doesntexist")
+	assert.ErrorIs(t, err, fs.ErrNotExist)
+
+	_, err = fakefs.Open("file")
+	assert.NoError(t, err)
+}

libs/filer/completer/completer_test.go

@@ -6,6 +6,7 @@ import (
 	"testing"
 
 	"github.com/databricks/cli/cmd/root"
+	"github.com/databricks/cli/libs/fakefs"
 	"github.com/databricks/cli/libs/filer"
 	"github.com/databricks/databricks-sdk-go/experimental/mocks"
 	"github.com/spf13/cobra"
@@ -17,7 +18,7 @@ func setupCompleter(t *testing.T, onlyDirs bool) *completer {
 	// Needed to make type context.valueCtx for mockFilerForPath
 	ctx = root.SetWorkspaceClient(ctx, mocks.NewMockWorkspaceClient(t).WorkspaceClient)
 
-	fakeFiler := filer.NewFakeFiler(map[string]filer.FakeFileInfo{
+	fakeFiler := filer.NewFakeFiler(map[string]fakefs.FileInfo{
 		"dir":       {FakeName: "root", FakeDir: true},
 		"dir/dirA":  {FakeDir: true},
 		"dir/dirB":  {FakeDir: true},

libs/filer/fake_filer.go

@@ -8,58 +8,12 @@ import (
 	"path"
 	"sort"
 	"strings"
-	"time"
+
+	"github.com/databricks/cli/libs/fakefs"
 )
 
-type FakeDirEntry struct {
-	FakeFileInfo
-}
-
-func (entry FakeDirEntry) Type() fs.FileMode {
-	typ := fs.ModePerm
-	if entry.FakeDir {
-		typ |= fs.ModeDir
-	}
-	return typ
-}
-
-func (entry FakeDirEntry) Info() (fs.FileInfo, error) {
-	return entry.FakeFileInfo, nil
-}
-
-type FakeFileInfo struct {
-	FakeName string
-	FakeSize int64
-	FakeDir  bool
-	FakeMode fs.FileMode
-}
-
-func (info FakeFileInfo) Name() string {
-	return info.FakeName
-}
-
-func (info FakeFileInfo) Size() int64 {
-	return info.FakeSize
-}
-
-func (info FakeFileInfo) Mode() fs.FileMode {
-	return info.FakeMode
-}
-
-func (info FakeFileInfo) ModTime() time.Time {
-	return time.Now()
-}
-
-func (info FakeFileInfo) IsDir() bool {
-	return info.FakeDir
-}
-
-func (info FakeFileInfo) Sys() any {
-	return nil
-}
-
 type FakeFiler struct {
-	entries map[string]FakeFileInfo
+	entries map[string]fakefs.FileInfo
 }
 
 func (f *FakeFiler) Write(ctx context.Context, p string, reader io.Reader, mode ...WriteMode) error {
@@ -97,7 +51,7 @@ func (f *FakeFiler) ReadDir(ctx context.Context, p string) ([]fs.DirEntry, error
 			continue
 		}
 
-		out = append(out, FakeDirEntry{v})
+		out = append(out, fakefs.DirEntry{FileInfo: v})
 	}
 
 	sort.Slice(out, func(i, j int) bool { return out[i].Name() < out[j].Name() })
@@ -117,7 +71,11 @@ func (f *FakeFiler) Stat(ctx context.Context, path string) (fs.FileInfo, error)
 	return entry, nil
 }
 
-func NewFakeFiler(entries map[string]FakeFileInfo) *FakeFiler {
+// NewFakeFiler creates a new fake [Filer] instance with the given entries.
+// It sets the [Name] field of each entry to the base name of the path.
+//
+// This is meant to be used in tests.
+func NewFakeFiler(entries map[string]fakefs.FileInfo) *FakeFiler {
 	fakeFiler := &FakeFiler{
 		entries: entries,
 	}

libs/filer/fake_filer_test.go

@@ -0,0 +1,98 @@
+package filer
+
+import (
+	"context"
+	"io"
+	"io/fs"
+	"testing"
+
+	"github.com/databricks/cli/libs/fakefs"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestFakeFiler_Read(t *testing.T) {
+	f := NewFakeFiler(map[string]fakefs.FileInfo{
+		"file": {},
+	})
+
+	ctx := context.Background()
+	r, err := f.Read(ctx, "file")
+	require.NoError(t, err)
+	contents, err := io.ReadAll(r)
+	require.NoError(t, err)
+
+	// Contents of every file is "foo".
+	assert.Equal(t, "foo", string(contents))
+}
+
+func TestFakeFiler_Read_NotFound(t *testing.T) {
+	f := NewFakeFiler(map[string]fakefs.FileInfo{
+		"foo": {},
+	})
+
+	ctx := context.Background()
+	_, err := f.Read(ctx, "bar")
+	assert.ErrorIs(t, err, fs.ErrNotExist)
+}
+
+func TestFakeFiler_ReadDir_NotFound(t *testing.T) {
+	f := NewFakeFiler(map[string]fakefs.FileInfo{
+		"dir1": {FakeDir: true},
+	})
+
+	ctx := context.Background()
+	_, err := f.ReadDir(ctx, "dir2")
+	assert.ErrorIs(t, err, fs.ErrNotExist)
+}
+
+func TestFakeFiler_ReadDir_NotADirectory(t *testing.T) {
+	f := NewFakeFiler(map[string]fakefs.FileInfo{
+		"file": {},
+	})
+
+	ctx := context.Background()
+	_, err := f.ReadDir(ctx, "file")
+	assert.ErrorIs(t, err, fs.ErrInvalid)
+}
+
+func TestFakeFiler_ReadDir(t *testing.T) {
+	f := NewFakeFiler(map[string]fakefs.FileInfo{
+		"dir1":       {FakeDir: true},
+		"dir1/file2": {},
+		"dir1/dir2":  {FakeDir: true},
+	})
+
+	ctx := context.Background()
+	entries, err := f.ReadDir(ctx, "dir1/")
+	require.NoError(t, err)
+	require.Len(t, entries, 2)
+
+	// The entries are sorted by name.
+	assert.Equal(t, "dir2", entries[0].Name())
+	assert.True(t, entries[0].IsDir())
+	assert.Equal(t, "file2", entries[1].Name())
+	assert.False(t, entries[1].IsDir())
+}
+
+func TestFakeFiler_Stat(t *testing.T) {
+	f := NewFakeFiler(map[string]fakefs.FileInfo{
+		"file": {},
+	})
+
+	ctx := context.Background()
+	info, err := f.Stat(ctx, "file")
+	require.NoError(t, err)
+
+	assert.Equal(t, "file", info.Name())
+}
+
+func TestFakeFiler_Stat_NotFound(t *testing.T) {
+	f := NewFakeFiler(map[string]fakefs.FileInfo{
+		"foo": {},
+	})
+
+	ctx := context.Background()
+	_, err := f.Stat(ctx, "bar")
+	assert.ErrorIs(t, err, fs.ErrNotExist)
+}

libs/filer/fs_test.go

@@ -6,6 +6,7 @@ import (
 	"io/fs"
 	"testing"
 
+	"github.com/databricks/cli/libs/fakefs"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
@@ -35,7 +36,7 @@ func TestFsDirImplementsFsReadDirFile(t *testing.T) {
 }
 
 func fakeFS() fs.FS {
-	fakeFiler := NewFakeFiler(map[string]FakeFileInfo{
+	fakeFiler := NewFakeFiler(map[string]fakefs.FileInfo{
 		".":     {FakeName: "root", FakeDir: true},
 		"dirA":  {FakeDir: true},
 		"dirB":  {FakeDir: true},

libs/notebook/detect_test.go

@@ -7,6 +7,7 @@ import (
 	"path/filepath"
 	"testing"
 
+	"github.com/databricks/cli/libs/fakefs"
 	"github.com/databricks/databricks-sdk-go/service/workspace"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
@@ -100,11 +101,21 @@ func TestDetectFileWithLongHeader(t *testing.T) {
 	assert.False(t, nb)
 }
 
+type fileInfoWithWorkspaceInfo struct {
+	fakefs.FileInfo
+
+	oi workspace.ObjectInfo
+}
+
+func (f fileInfoWithWorkspaceInfo) WorkspaceObjectInfo() workspace.ObjectInfo {
+	return f.oi
+}
+
 func TestDetectWithObjectInfo(t *testing.T) {
-	fakeFS := &fakeFS{
-		fakeFile{
-			fakeFileInfo{
-				workspace.ObjectInfo{
+	fakefs := fakefs.FS{
+		"file.py": fakefs.File{
+			FileInfo: fileInfoWithWorkspaceInfo{
+				oi: workspace.ObjectInfo{
 					ObjectType: workspace.ObjectTypeNotebook,
 					Language:   workspace.LanguagePython,
 				},
@@ -112,7 +123,7 @@ func TestDetectWithObjectInfo(t *testing.T) {
 		},
 	}
 
-	nb, lang, err := DetectWithFS(fakeFS, "doesntmatter")
+	nb, lang, err := DetectWithFS(fakefs, "file.py")
 	require.NoError(t, err)
 	assert.True(t, nb)
 	assert.Equal(t, workspace.LanguagePython, lang)

libs/notebook/fakefs_test.go

@@ -1,77 +0,0 @@
-package notebook
-
-import (
-	"fmt"
-	"io/fs"
-	"time"
-
-	"github.com/databricks/databricks-sdk-go/service/workspace"
-)
-
-type fakeFS struct {
-	fakeFile
-}
-
-type fakeFile struct {
-	fakeFileInfo
-}
-
-func (f fakeFile) Close() error {
-	return nil
-}
-
-func (f fakeFile) Read(p []byte) (n int, err error) {
-	return 0, fmt.Errorf("not implemented")
-}
-
-func (f fakeFile) Stat() (fs.FileInfo, error) {
-	return f.fakeFileInfo, nil
-}
-
-type fakeFileInfo struct {
-	oi workspace.ObjectInfo
-}
-
-func (f fakeFileInfo) WorkspaceObjectInfo() workspace.ObjectInfo {
-	return f.oi
-}
-
-func (f fakeFileInfo) Name() string {
-	return ""
-}
-
-func (f fakeFileInfo) Size() int64 {
-	return 0
-}
-
-func (f fakeFileInfo) Mode() fs.FileMode {
-	return 0
-}
-
-func (f fakeFileInfo) ModTime() time.Time {
-	return time.Time{}
-}
-
-func (f fakeFileInfo) IsDir() bool {
-	return false
-}
-
-func (f fakeFileInfo) Sys() any {
-	return nil
-}
-
-func (f fakeFS) Open(name string) (fs.File, error) {
-	return f.fakeFile, nil
-}
-
-func (f fakeFS) Stat(name string) (fs.FileInfo, error) {
-	panic("not implemented")
-}
-
-func (f fakeFS) ReadDir(name string) ([]fs.DirEntry, error) {
-	panic("not implemented")
-}
-
-func (f fakeFS) ReadFile(name string) ([]byte, error) {
-	panic("not implemented")
-}