refactor: improve tmux command (#59)

Restructuring the tmux package to use a central struct for command execution to help
with testability. It includes the use of a package level instance of
the new tmux.Command struct and an init function to initialize it. Once all of the
functions using the tmux cli are updated to use the Command struct directly that
code can be removed in favor of a single tmux.Command instance configured in the cli.

Author: markfeinstein

.github/workflows/ci-cd.yml

@@ -25,6 +25,10 @@ jobs:
           go-version: "1.21"
       - name: Install deps
         run: go install github.com/jstemmer/go-junit-report/v2@latest
+      - if: startsWith(matrix.os, 'macOS')
+        run: |
+          brew update
+          brew install tmux
       - name: Run tests
         run: go test -cover -bench=. -benchmem -race -v 2>&1 ./... | go-junit-report -set-exit-code > report.xml
       - name: Test Summary

tmux/list.go

@@ -156,12 +156,12 @@ func sortSessions(sessions []*TmuxSession) []*TmuxSession {
 
 func List(o Options) ([]*TmuxSession, error) {
 	format := format()
-	output, err := tmuxCmd([]string{"list-sessions", "-F", format})
-	cleanOutput := strings.TrimSpace(output)
-	if err != nil || strings.HasPrefix(cleanOutput, "no server running on") {
-		return nil, nil
+	output, err := command.Run([]string{"list-sessions", "-F", format})
+	if err != nil {
+		return nil, err
 	}
-	sessionList := strings.TrimSpace(string(output))
+
+	sessionList := output
 	lines := strings.Split(sessionList, "\n")
 	sessions := processSessions(o, lines)
 

tmux/list_test.go

@@ -1,6 +1,7 @@
 package tmux
 
 import (
+	_ "embed"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -86,6 +87,47 @@ func TestProcessSessions(t *testing.T) {
 	}
 }
 
+//go:embed testdata/session_list.txt
+var sessionList string
+
+func TestList(t *testing.T) {
+	testCase := map[string]struct {
+		MockResponse   string
+		MockError      error
+		Options        Options
+		ExpectedLength int
+		Error          error
+	}{
+		"happy path": {
+			MockResponse:   sessionList,
+			ExpectedLength: 3,
+		},
+		"happy path show hidden": {
+			MockResponse:   sessionList,
+			Options:        Options{HideAttached: true},
+			ExpectedLength: 2,
+		},
+	}
+
+	for name, tc := range testCase {
+		t.Run(name, func(t *testing.T) {
+			command = &Command{
+				execFunc: func(string, []string) (string, error) {
+					return tc.MockResponse, tc.MockError
+				},
+			}
+			res, err := List(tc.Options)
+			require.ErrorIs(t, tc.Error, err)
+			if err != nil {
+				return
+			}
+
+			require.Len(t, res, tc.ExpectedLength)
+			t.Log(res)
+		})
+	}
+}
+
 func BenchmarkProcessSessions(b *testing.B) {
 	for n := 0; n < b.N; n++ {
 		processSessions(Options{}, []string{

tmux/testdata/session_list.txt

@@ -0,0 +1,3 @@
+1706646951  1 /dev/ttys000 1706475706 1       0 $2 1706643877 0 0 sesh /Users/test_user/dev/sesh 2,1 2
+1706632190  0  1706485534 1       0 $8 1706632189 0 0 dotfiles /Users/test_user/dotfiles 1 1
+1706485830  0  1706485825 1       0 $10 1706485825 0 0 window-name /Users/test_user/test_user/tmux-nerd-font-window-name 1 1

tmux/tmux.go

@@ -7,11 +7,82 @@ import (
 	"os"
 	"os/exec"
 	"strings"
+	"sync"
 
 	"github.com/joshmedeski/sesh/config"
 	"github.com/joshmedeski/sesh/dir"
 )
 
+var (
+	command *Command
+	once    sync.Once
+)
+
+func init() {
+	once.Do(func() {
+		var err error
+		command, err = NewCommand()
+		if err != nil {
+			log.Fatal(err)
+		}
+	})
+}
+
+type Error struct{ msg string }
+
+func (e Error) Error() string { return e.msg }
+
+var ErrNotRunning = Error{"no server running"}
+
+func executeCommand(command string, args []string) (string, error) {
+	var stdout, stderr bytes.Buffer
+	cmd := exec.Command(command, args...)
+	cmd.Stdin = os.Stdin
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+
+	if err := cmd.Start(); err != nil {
+		return "", err
+	}
+
+	if err := cmd.Wait(); err != nil {
+		if strings.Contains(stderr.String(), "no server running on") {
+			return "", ErrNotRunning
+		}
+
+		return "", err
+	}
+
+	out := strings.TrimSpace(stdout.String())
+	if strings.Contains(out, "no server running on") {
+		return "", ErrNotRunning
+	}
+
+	return out, nil
+}
+
+type Command struct {
+	cliPath  string
+	execFunc func(string, []string) (string, error)
+}
+
+func NewCommand() (c *Command, err error) {
+	c = new(Command)
+
+	c.cliPath, err = exec.LookPath("tmux")
+	if err != nil {
+		return nil, err
+	}
+
+	c.execFunc = executeCommand
+
+	return c, nil
+}
+
+func (c *Command) Run(args []string) (string, error) {
+	return c.execFunc(c.cliPath, args)
+}
+
 func GetSession(s string) (TmuxSession, error) {
 	sessionList, err := List(Options{})
 	if err != nil {
@@ -41,27 +112,7 @@ func GetSession(s string) (TmuxSession, error) {
 }
 
 func tmuxCmd(args []string) (string, error) {
-	tmux, err := exec.LookPath("tmux")
-	if err != nil {
-		return "", err
-	}
-	var stdout, stderr bytes.Buffer
-	cmd := exec.Command(tmux, args...)
-	cmd.Stdin = os.Stdin
-	cmd.Stdout = &stdout
-	cmd.Stderr = os.Stderr
-	cmd.Stderr = &stderr
-	if err := cmd.Start(); err != nil {
-		return "", err
-	}
-	if err := cmd.Wait(); err != nil {
-		errString := strings.TrimSpace(stderr.String())
-		if strings.HasPrefix(errString, "no server running on") {
-			return "", nil
-		}
-		return "", err
-	}
-	return stdout.String(), nil
+	return command.Run(args)
 }
 
 func isAttached() bool {