Run shellcheck on bash completion

bash_completions_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"fmt"
 	"os"
+	"os/exec"
 	"strings"
 	"testing"
 )
@@ -23,6 +24,26 @@ func check(t *testing.T, found, expected string) {
 	}
 }
 
+func runShellCheck(s string) error {
+	excluded := []string{
+		"SC2034", // PREFIX appears unused. Verify it or export it.
+	}
+	cmd := exec.Command("shellcheck", "-s", "bash", "-", "-e", strings.Join(excluded, ","))
+	cmd.Stderr = os.Stderr
+	cmd.Stdout = os.Stdout
+
+	stdin, err := cmd.StdinPipe()
+	if err != nil {
+		return err
+	}
+	go func() {
+		defer stdin.Close()
+		stdin.Write([]byte(s))
+	}()
+
+	return cmd.Run()
+}
+
 // World worst custom function, just keep telling you to enter hello!
 const (
 	bashCompletionFunc = `__custom_func() {
@@ -107,4 +128,13 @@ func TestBashCompletions(t *testing.T) {
 	check(t, str, `flags_completion+=("__handle_subdirs_in_dir_flag themes")`)
 
 	checkOmit(t, str, cmdDeprecated.Name())
+
+	// if available, run shellcheck against the script
+	if err := exec.Command("which", "shellcheck").Run(); err != nil {
+		return
+	}
+	err := runShellCheck(str)
+	if err != nil {
+		t.Fatalf("shellcheck failed: %v", err)
+	}
 }