[javascript processor] Lint and add tests (#47813)

Add tests for libbeat/processors/script/javascript/javascript.go in preparation for #46988.

Additionally, fix golangci-lint, run the modernizer and fix some typos.

- Relates #46988

Author: orestisfl

libbeat/processors/script/javascript/beatevent_v0.go

@@ -18,8 +18,8 @@
 package javascript
 
 import (
-	"errors"
 	"fmt"
+	"slices"
 
 	"github.com/dop251/goja"
 
@@ -28,8 +28,8 @@ import (
 )
 
 // IMPORTANT:
-// This is the user facing API within Javascript processors. Do not make
-// breaking changes to the JS methods. If you must make breaking changes then
+// This is the user-facing API within JavaScript processors. Do not make
+// breaking changes to the JS methods. If you must make breaking changes, then
 // create a new version and require the user to specify an API version in their
 // configuration (e.g. api_version: 2).
 
@@ -52,48 +52,47 @@ func newBeatEventV0(s Session) (Event, error) {
 func newBeatEventV0Constructor(s Session) func(call goja.ConstructorCall) *goja.Object {
 	return func(call goja.ConstructorCall) *goja.Object {
 		if len(call.Arguments) != 1 {
-			panic(errors.New("Event constructor requires one argument"))
+			panic("Event constructor requires one argument")
 		}
 
 		a0 := call.Argument(0).Export()
 
 		var fields mapstr.M
 		switch v := a0.(type) {
-		case map[string]interface{}:
+		case map[string]any:
 			fields = v
 		case mapstr.M:
 			fields = v
 		default:
-			panic(fmt.Errorf("Event constructor requires a "+
-				"map[string]interface{} argument but got %T", a0))
+			panic(fmt.Sprintf("Event constructor requires map[string]interface{} argument but got %T", a0))
 		}
 
 		evt := &beatEventV0{
 			vm:  s.Runtime(),
 			obj: call.This,
 		}
 		evt.init()
-		evt.reset(&beat.Event{Fields: fields})
+		_ = evt.reset(&beat.Event{Fields: fields})
 		return nil
 	}
 }
 
 func (e *beatEventV0) init() {
-	e.obj.Set("Get", e.get)
-	e.obj.Set("Put", e.put)
-	e.obj.Set("Rename", e.rename)
-	e.obj.Set("Delete", e.delete)
-	e.obj.Set("Cancel", e.cancel)
-	e.obj.Set("Tag", e.tag)
-	e.obj.Set("AppendTo", e.appendTo)
+	_ = e.obj.Set("Get", e.get)
+	_ = e.obj.Set("Put", e.put)
+	_ = e.obj.Set("Rename", e.rename)
+	_ = e.obj.Set("Delete", e.delete)
+	_ = e.obj.Set("Cancel", e.cancel)
+	_ = e.obj.Set("Tag", e.tag)
+	_ = e.obj.Set("AppendTo", e.appendTo)
 }
 
 // reset the event so that it can be reused to wrap another event.
 func (e *beatEventV0) reset(b *beat.Event) error {
 	e.inner = b
 	e.cancelled = false
-	e.obj.Set("_private", e)
-	e.obj.Set("fields", e.vm.ToValue(e.inner.Fields))
+	_ = e.obj.Set("_private", e)
+	_ = e.obj.Set("fields", e.vm.ToValue(e.inner.Fields))
 	return nil
 }
 
@@ -103,13 +102,13 @@ func (e *beatEventV0) Wrapped() *beat.Event {
 }
 
 // JSObject returns the goja.Value that represents the event within the
-// Javascript runtime.
+// JavaScript runtime.
 func (e *beatEventV0) JSObject() goja.Value {
 	return e.obj
 }
 
-// get returns the specified field. If the field does not exist then null is
-// returned. If no field is specified then it returns entire object.
+// get returns the specified field. If the field does not exist, then null is
+// returned. If no field is specified, then it returns an entire object.
 //
 //	// javascript
 //	var dataset = evt.Get("event.dataset");
@@ -129,7 +128,7 @@ func (e *beatEventV0) get(call goja.FunctionCall) goja.Value {
 }
 
 // put writes a value to the event. If there was a previous value assigned to
-// the given field then the old object is returned. It throws an exception if
+// the given field, then the old object is returned. It throws an exception if
 // you try to write a to a field where one of the intermediate values is not
 // an object.
 //
@@ -138,7 +137,7 @@ func (e *beatEventV0) get(call goja.FunctionCall) goja.Value {
 //	evt.Put("geo.location", {"lon": -73.614830, "lat": 45.505918});
 func (e *beatEventV0) put(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) != 2 {
-		panic(errors.New("Put requires two arguments (key and value)"))
+		panic("Put requires two arguments (key and value)")
 	}
 
 	key := call.Argument(0).String()
@@ -157,7 +156,7 @@ func (e *beatEventV0) put(call goja.FunctionCall) goja.Value {
 //	evt.Rename("src_ip", "source.ip");
 func (e *beatEventV0) rename(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) != 2 {
-		panic(errors.New("Rename requires two arguments (from and to)"))
+		panic("Rename requires two arguments (from and to)")
 	}
 
 	from := call.Argument(0).String()
@@ -181,7 +180,7 @@ func (e *beatEventV0) rename(call goja.FunctionCall) goja.Value {
 
 	if _, err = e.inner.PutValue(to, fromValue); err != nil {
 		// Undo
-		e.inner.PutValue(from, fromValue)
+		_, _ = e.inner.PutValue(from, fromValue)
 		return e.vm.ToValue(false)
 	}
 
@@ -194,7 +193,7 @@ func (e *beatEventV0) rename(call goja.FunctionCall) goja.Value {
 //	evt.Delete("http.request.headers.authorization");
 func (e *beatEventV0) delete(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) != 1 {
-		panic(errors.New("Delete requires one argument"))
+		panic("Delete requires one argument")
 	}
 
 	key := call.Argument(0).String()
@@ -210,14 +209,14 @@ func (e *beatEventV0) IsCancelled() bool {
 	return e.cancelled
 }
 
-// Cancel marks the event as cancelled. When the processor returns the event
+// Cancel marks the event as cancelled. When the processor returns, the event
 // will be dropped.
 func (e *beatEventV0) Cancel() {
 	e.cancelled = true
 }
 
 // cancel marks the event as cancelled.
-func (e *beatEventV0) cancel(call goja.FunctionCall) goja.Value {
+func (e *beatEventV0) cancel(goja.FunctionCall) goja.Value {
 	e.cancelled = true
 	return goja.Undefined()
 }
@@ -229,7 +228,7 @@ func (e *beatEventV0) cancel(call goja.FunctionCall) goja.Value {
 //	evt.Tag("_parse_failure");
 func (e *beatEventV0) tag(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) != 1 {
-		panic(errors.New("Tag requires one argument"))
+		panic("Tag requires one argument")
 	}
 
 	tag := call.Argument(0).String()
@@ -242,14 +241,14 @@ func (e *beatEventV0) tag(call goja.FunctionCall) goja.Value {
 
 // appendTo is a specialized Put method that converts any existing value to
 // an array and appends the value if it does not already exist. If there is an
-// existing value that's not a string or array of strings then an exception is
+// existing value that's not a string or array of strings, then an exception is
 // thrown.
 //
 //	// javascript
 //	evt.AppendTo("error.message", "invalid file hash");
 func (e *beatEventV0) appendTo(call goja.FunctionCall) goja.Value {
 	if len(call.Arguments) != 2 {
-		panic(errors.New("AppendTo requires two arguments (field and value)"))
+		panic("AppendTo requires two arguments (field and value)")
 	}
 
 	field := call.Argument(0).String()
@@ -275,14 +274,12 @@ func appendString(m mapstr.M, field, value string, alwaysArray bool) error {
 			m.Put(field, []string{v, value})
 		}
 	case []string:
-		for _, existingTag := range v {
-			if value == existingTag {
-				// Duplicate
-				return nil
-			}
+		if slices.Contains(v, value) {
+			// Duplicate
+			return nil
 		}
 		m.Put(field, append(v, value))
-	case []interface{}:
+	case []any:
 		for _, existingTag := range v {
 			if value == existingTag {
 				// Duplicate

libbeat/processors/script/javascript/beatevent_v0_test.go

@@ -197,7 +197,7 @@ func TestBeatEventV0(t *testing.T) {
 			// Validate that the processor's metrics exist.
 			var found bool
 			prefix := fmt.Sprintf("processor.javascript.%s.histogram.process_time", tc.name)
-			reg.Do(monitoring.Full, func(name string, v interface{}) {
+			reg.Do(monitoring.Full, func(name string, v any) {
 				if !found && strings.HasPrefix(name, prefix) {
 					found = true
 				}
@@ -221,7 +221,7 @@ func BenchmarkBeatEventV0(b *testing.B) {
 
 			event := testEvent()
 			b.ResetTimer()
-			for i := 0; i < b.N; i++ {
+			for b.Loop() {
 				_, err := p.Run(event)
 				if err != nil {
 					b.Fatal(err)

libbeat/processors/script/javascript/config.go

@@ -22,17 +22,17 @@ import (
 	"time"
 )
 
-// Config defines the Javascript source files to use for the processor.
+// Config defines the JavaScript source files to use for the processor.
 type Config struct {
-	Tag                string                 `config:"tag"`                                  // Processor ID for debug and metrics.
-	Source             string                 `config:"source"`                               // Inline script to execute.
-	File               string                 `config:"file"`                                 // Source file.
-	Files              []string               `config:"files"`                                // Multiple source files.
-	Params             map[string]interface{} `config:"params"`                               // Parameters to pass to script.
-	Timeout            time.Duration          `config:"timeout" validate:"min=0"`             // Execution timeout.
-	TagOnException     string                 `config:"tag_on_exception"`                     // Tag to add to events when an exception happens.
-	MaxCachedSessions  int                    `config:"max_cached_sessions" validate:"min=0"` // Max. number of cached VM sessions.
-	OnlyCachedSessions bool                   `config:"only_cached_sessions"`                 // Only use cached VM sessions.
+	Tag                string         `config:"tag"`                                  // Processor ID for debug and metrics.
+	Source             string         `config:"source"`                               // Inline script to execute.
+	File               string         `config:"file"`                                 // Source file.
+	Files              []string       `config:"files"`                                // Multiple source files.
+	Params             map[string]any `config:"params"`                               // Parameters to pass to script.
+	Timeout            time.Duration  `config:"timeout" validate:"min=0"`             // Execution timeout.
+	TagOnException     string         `config:"tag_on_exception"`                     // Tag to add to events when an exception happens.
+	MaxCachedSessions  int            `config:"max_cached_sessions" validate:"min=0"` // Max. number of cached VM sessions.
+	OnlyCachedSessions bool           `config:"only_cached_sessions"`                 // Only use cached VM sessions.
 }
 
 // Validate returns an error if one (and only one) option is not set.

libbeat/processors/script/javascript/javascript.go

@@ -47,7 +47,7 @@ type jsProcessor struct {
 	stats       *processorStats
 }
 
-// New constructs a new Javascript processor.
+// New constructs a new JavaScript processor.
 func New(c *config.C, log *logp.Logger) (beat.Processor, error) {
 	conf := defaultConfig()
 	if err := c.Unpack(&conf); err != nil {
@@ -57,7 +57,7 @@ func New(c *config.C, log *logp.Logger) (beat.Processor, error) {
 	return NewFromConfig(conf, monitoring.Default, log)
 }
 
-// NewFromConfig constructs a new Javascript processor from the given config
+// NewFromConfig constructs a new JavaScript processor from the given config
 // object. It loads the sources, compiles them, and validates the entry point.
 func NewFromConfig(c Config, reg *monitoring.Registry, logger *logp.Logger) (beat.Processor, error) {
 	err := c.Validate()
@@ -66,12 +66,11 @@ func NewFromConfig(c Config, reg *monitoring.Registry, logger *logp.Logger) (bea
 	}
 
 	var sourceFile string
-	var sourceCode []byte
-
+	var sourceCode string
 	switch {
 	case c.Source != "":
 		sourceFile = "inline.js"
-		sourceCode = []byte(c.Source)
+		sourceCode = c.Source
 	case c.File != "":
 		sourceFile, sourceCode, err = loadSources(c.File)
 	case len(c.Files) > 0:
@@ -82,7 +81,7 @@ func NewFromConfig(c Config, reg *monitoring.Registry, logger *logp.Logger) (bea
 	}
 
 	// Validate processor source code.
-	prog, err := goja.Compile(sourceFile, string(sourceCode), true)
+	prog, err := goja.Compile(sourceFile, sourceCode, true)
 	if err != nil {
 		return nil, err
 	}
@@ -102,7 +101,7 @@ func NewFromConfig(c Config, reg *monitoring.Registry, logger *logp.Logger) (bea
 }
 
 // loadSources loads javascript source from files.
-func loadSources(files ...string) (string, []byte, error) {
+func loadSources(files ...string) (string, string, error) {
 	var sources []string
 	buf := new(bytes.Buffer)
 
@@ -131,7 +130,7 @@ func loadSources(files ...string) (string, []byte, error) {
 		if hasMeta(filePath) {
 			matches, err := filepath.Glob(filePath)
 			if err != nil {
-				return "", nil, err
+				return "", "", err
 			}
 			sources = append(sources, matches...)
 		} else {
@@ -140,17 +139,17 @@ func loadSources(files ...string) (string, []byte, error) {
 	}
 
 	if len(sources) == 0 {
-		return "", nil, fmt.Errorf("no sources were found in %v",
+		return "", "", fmt.Errorf("no sources were found in %v",
 			strings.Join(files, ", "))
 	}
 
 	for _, name := range sources {
 		if err := readFile(name); err != nil {
-			return "", nil, err
+			return "", "", err
 		}
 	}
 
-	return strings.Join(sources, ";"), buf.Bytes(), nil
+	return strings.Join(sources, ";"), buf.String(), nil
 }
 
 func annotateError(id string, err error) error {
@@ -164,7 +163,7 @@ func annotateError(id string, err error) error {
 }
 
 // Run executes the processor on the given it event. It invokes the
-// process function defined in the Javascript source.
+// process function defined in the JavaScript source.
 func (p *jsProcessor) Run(event *beat.Event) (*beat.Event, error) {
 	s := p.sessionPool.Get()
 	defer p.sessionPool.Put(s)