add flush-dns tests for all platforms and refactor command definitions

Extract getDNSCommands() to separate command definitions from execution,
enabling testable platform-specific DNS flush commands for macOS, Windows,
and Linux. Add BDD-style tests using Ginkgo/Gomega.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: qdriven

cmd/magic/flush_dns.go

@@ -30,6 +30,29 @@ Platform-specific commands used:
 	},
 }
 
+func getDNSCommands(osName string) ([][]string, error) {
+	switch osName {
+	case "darwin":
+		return [][]string{
+			{"sudo", "dscacheutil", "-flushcache"},
+			{"sudo", "killall", "-HUP", "mDNSResponder"},
+		}, nil
+	case "windows":
+		return [][]string{
+			{"ipconfig", "/flushdns"},
+		}, nil
+	case "linux":
+		return [][]string{
+			{"sudo", "systemctl", "restart", "systemd-resolved"},
+			{"sudo", "service", "nscd", "restart"},
+			{"sudo", "service", "dnsmasq", "restart"},
+			{"sudo", "rndc", "flush"},
+		}, nil
+	default:
+		return nil, fmt.Errorf("unsupported operating system: %s", osName)
+	}
+}
+
 func flushDNS() error {
 	osName := runtime.GOOS
 
@@ -51,10 +74,7 @@ func flushDNS() error {
 func flushDNSMac() error {
 	pterm.Info.Println("Flushing DNS cache on macOS...")
 
-	commands := [][]string{
-		{"sudo", "dscacheutil", "-flushcache"},
-		{"sudo", "killall", "-HUP", "mDNSResponder"},
-	}
+	commands, _ := getDNSCommands("darwin")
 
 	for _, cmdArgs := range commands {
 		cmd := exec.Command(cmdArgs[0], cmdArgs[1:]...)
@@ -74,7 +94,10 @@ func flushDNSMac() error {
 func flushDNSWindows() error {
 	pterm.Info.Println("Flushing DNS cache on Windows...")
 
-	cmd := exec.Command("ipconfig", "/flushdns")
+	commands, _ := getDNSCommands("windows")
+	cmdArgs := commands[0]
+
+	cmd := exec.Command(cmdArgs[0], cmdArgs[1:]...)
 	cmd.Stdout = os.Stdout
 	cmd.Stderr = os.Stderr
 
@@ -89,15 +112,10 @@ func flushDNSWindows() error {
 func flushDNSLinux() error {
 	pterm.Info.Println("Flushing DNS cache on Linux...")
 
-	flushMethods := [][]string{
-		{"sudo", "systemctl", "restart", "systemd-resolved"},
-		{"sudo", "service", "nscd", "restart"},
-		{"sudo", "service", "dnsmasq", "restart"},
-		{"sudo", "rndc", "flush"},
-	}
+	commands, _ := getDNSCommands("linux")
 
 	var lastErr error
-	for _, cmdArgs := range flushMethods {
+	for _, cmdArgs := range commands {
 		cmd := exec.Command(cmdArgs[0], cmdArgs[1:]...)
 		cmd.Stdout = os.Stdout
 		cmd.Stderr = os.Stderr

cmd/magic/flush_dns_test.go

@@ -0,0 +1,62 @@
+package magic
+
+import (
+	"runtime"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("FlushDNS", func() {
+	Describe("getDNSCommands", func() {
+		Context("on macOS", func() {
+			It("should return dscacheutil and killall commands", func() {
+				commands, err := getDNSCommands("darwin")
+				Expect(err).NotTo(HaveOccurred())
+				Expect(commands).To(HaveLen(2))
+				Expect(commands[0]).To(Equal([]string{"sudo", "dscacheutil", "-flushcache"}))
+				Expect(commands[1]).To(Equal([]string{"sudo", "killall", "-HUP", "mDNSResponder"}))
+			})
+		})
+
+		Context("on Windows", func() {
+			It("should return ipconfig flushdns command", func() {
+				commands, err := getDNSCommands("windows")
+				Expect(err).NotTo(HaveOccurred())
+				Expect(commands).To(HaveLen(1))
+				Expect(commands[0]).To(Equal([]string{"ipconfig", "/flushdns"}))
+			})
+		})
+
+		Context("on Linux", func() {
+			It("should return multiple flush methods", func() {
+				commands, err := getDNSCommands("linux")
+				Expect(err).NotTo(HaveOccurred())
+				Expect(commands).To(HaveLen(4))
+				Expect(commands[0]).To(Equal([]string{"sudo", "systemctl", "restart", "systemd-resolved"}))
+				Expect(commands[1]).To(Equal([]string{"sudo", "service", "nscd", "restart"}))
+				Expect(commands[2]).To(Equal([]string{"sudo", "service", "dnsmasq", "restart"}))
+				Expect(commands[3]).To(Equal([]string{"sudo", "rndc", "flush"}))
+			})
+		})
+
+		Context("on unsupported OS", func() {
+			It("should return an error", func() {
+				_, err := getDNSCommands("freebsd")
+				Expect(err).To(HaveOccurred())
+				Expect(err.Error()).To(ContainSubstring("unsupported operating system: freebsd"))
+			})
+		})
+	})
+
+	Describe("flushDNS routing", func() {
+		Context("on the current platform", func() {
+			It("should not return unsupported OS error", func() {
+				err := flushDNS()
+				if runtime.GOOS == "darwin" || runtime.GOOS == "windows" || runtime.GOOS == "linux" {
+					Expect(err).NotTo(HaveOccurred())
+				}
+			})
+		})
+	})
+})

cmd/magic/magic_suite_test.go

@@ -0,0 +1,13 @@
+package magic
+
+import (
+	"testing"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+func TestMagic(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Magic Suite")
+}