Add string representation of Direction.

Allow to print Direction in human form.
Extract Direction struct to a separate file.
Add tests to cover Direction to string.
Parse direction from string with a new method stream.ParseDirection.
It returns direction or error if could not parse.

CHANGELOG.md

@@ -7,6 +7,8 @@
 * Add TimeoutHandler for the HTTP API server. (#420, @miry)
 * Set Write and Read timeouts for HTTP API server connections. (#423, @miry)
 * Show uniq request id in API HTTP response. (#425, @miry)
+* Add method to parse `stream.Direction` from string.
+  Allow to convert `stream.Direction` to string. (#430, @miry)
 
 # [2.4.0] - 2022-03-07
 

link.go

@@ -241,8 +241,5 @@ func (link *ToxicLink) RemoveToxic(toxic *toxics.ToxicWrapper) {
 
 // Direction returns the direction of the link (upstream or downstream).
 func (link *ToxicLink) Direction() string {
-	if link.direction == stream.Upstream {
-		return "upstream"
-	}
-	return "downstream"
+	return link.direction.String()
 }

stream/direction.go

@@ -0,0 +1,34 @@
+package stream
+
+import (
+	"errors"
+	"strings"
+)
+
+type Direction uint8
+
+var ErrInvalidDirectionParameter error = errors.New("stream: invalid direction")
+
+const (
+	Upstream Direction = iota
+	Downstream
+	NumDirections
+)
+
+func (d Direction) String() string {
+	if d >= NumDirections {
+		return "num_directions"
+	}
+	return [...]string{"upstream", "downstream"}[d]
+}
+
+func ParseDirection(value string) (Direction, error) {
+	switch strings.ToLower(value) {
+	case "downstream":
+		return Downstream, nil
+	case "upstream":
+		return Upstream, nil
+	}
+
+	return NumDirections, ErrInvalidDirectionParameter
+}

stream/direction_test.go

@@ -0,0 +1,67 @@
+package stream_test
+
+import (
+	"testing"
+
+	"github.com/Shopify/toxiproxy/v2/stream"
+)
+
+func TestDirection_String(t *testing.T) {
+	testCases := []struct {
+		name      string
+		direction stream.Direction
+		expected  string
+	}{
+		{"Downstream to string", stream.Downstream, "downstream"},
+		{"Upstream to string", stream.Upstream, "upstream"},
+		{"NumDirections to string", stream.NumDirections, "num_directions"},
+		{"Upstream via number direction to string", stream.Direction(0), "upstream"},
+		{"Downstream via number direction to string", stream.Direction(1), "downstream"},
+		{"High number direction to string", stream.Direction(5), "num_directions"},
+	}
+
+	for _, tc := range testCases {
+		tc := tc // capture range variable
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			actual := tc.direction.String()
+			if actual != tc.expected {
+				t.Errorf("got \"%s\"; expected \"%s\"", actual, tc.expected)
+			}
+		})
+	}
+}
+
+func TestParseDirection(t *testing.T) {
+	testCases := []struct {
+		name     string
+		input    string
+		expected stream.Direction
+		err      error
+	}{
+		{"parse empty", "", stream.NumDirections, stream.ErrInvalidDirectionParameter},
+		{"parse upstream", "upstream", stream.Upstream, nil},
+		{"parse downstream", "downstream", stream.Downstream, nil},
+		{"parse unknown", "unknown", stream.NumDirections, stream.ErrInvalidDirectionParameter},
+		{"parse number", "-123", stream.NumDirections, stream.ErrInvalidDirectionParameter},
+		{"parse upper case", "DOWNSTREAM", stream.Downstream, nil},
+		{"parse camel case", "UpStream", stream.Upstream, nil},
+	}
+
+	for _, tc := range testCases {
+		tc := tc // capture range variable
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			actual, err := stream.ParseDirection(tc.input)
+			if actual != tc.expected {
+				t.Errorf("got \"%s\"; expected \"%s\"", actual, tc.expected)
+			}
+
+			if err != tc.err {
+				t.Errorf("got \"%s\"; expected \"%s\"", err, tc.err)
+			}
+		})
+	}
+}

stream/io_chan.go

@@ -6,14 +6,6 @@ import (
 	"time"
 )
 
-type Direction uint8
-
-const (
-	Upstream Direction = iota
-	Downstream
-	NumDirections
-)
-
 // Stores a slice of bytes with its receive timestamp.
 type StreamChunk struct {
 	Data      []byte

toxic_collection.go

@@ -5,7 +5,6 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"strings"
 	"sync"
 
 	"github.com/rs/zerolog"
@@ -98,14 +97,11 @@ func (c *ToxicCollection) AddToxicJson(data io.Reader) (*toxics.ToxicWrapper, er
 		return nil, joinError(err, ErrBadRequestBody)
 	}
 
-	switch strings.ToLower(wrapper.Stream) {
-	case "downstream":
-		wrapper.Direction = stream.Downstream
-	case "upstream":
-		wrapper.Direction = stream.Upstream
-	default:
+	wrapper.Direction, err = stream.ParseDirection(wrapper.Stream)
+	if err != nil {
 		return nil, ErrInvalidStream
 	}
+
 	if wrapper.Name == "" {
 		wrapper.Name = fmt.Sprintf("%s_%s", wrapper.Type, wrapper.Stream)
 	}