diff --git a/internal/driver/ioscompanion/transport/grpc_test.go b/internal/driver/ioscompanion/transport/grpc_test.go
new file mode 100644
index 0000000..05b00bf
--- /dev/null
+++ b/internal/driver/ioscompanion/transport/grpc_test.go
@@ -0,0 +1,97 @@
+package transport
+
+import (
+	"archive/tar"
+	"bytes"
+	"compress/gzip"
+	"io"
+	"os"
+	"path/filepath"
+	"testing"
+
+	pb "github.com/priyanshujain/sanderling/internal/driver/ioscompanion/companionpb"
+)
+
+// grpcCompanion must satisfy Companion.
+var _ Companion = (*grpcCompanion)(nil)
+
+func TestDialReturnsCompanion(t *testing.T) {
+	companion, err := Dial("127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("Dial: %v", err)
+	}
+	defer companion.Close()
+	if companion == nil {
+		t.Fatal("Dial returned nil companion")
+	}
+}
+
+func TestProcessStateFromProto(t *testing.T) {
+	cases := []struct {
+		in   pb.InstalledAppInfo_AppProcessState
+		want ProcessState
+	}{
+		{pb.InstalledAppInfo_RUNNING, ProcessStateRunning},
+		{pb.InstalledAppInfo_NOT_RUNNING, ProcessStateNotRunning},
+		{pb.InstalledAppInfo_UNKNOWN, ProcessStateUnknown},
+	}
+	for _, c := range cases {
+		if got := processStateFromProto(c.in); got != c.want {
+			t.Errorf("processStateFromProto(%v) = %v, want %v", c.in, got, c.want)
+		}
+	}
+}
+
+func TestTarGzipDirectory(t *testing.T) {
+	root := t.TempDir()
+	bundle := filepath.Join(root, "Sample.app")
+	if err := os.MkdirAll(filepath.Join(bundle, "PlugIns"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(bundle, "Info.plist"), []byte("plist"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(bundle, "PlugIns", "ext"), []byte("x"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	archive, err := tarGzipDirectory(bundle)
+	if err != nil {
+		t.Fatalf("tarGzipDirectory: %v", err)
+	}
+
+	names := tarEntryNames(t, archive)
+	want := map[string]bool{
+		"Sample.app":             true,
+		"Sample.app/Info.plist":  true,
+		"Sample.app/PlugIns":     true,
+		"Sample.app/PlugIns/ext": true,
+	}
+	for name := range want {
+		if !names[name] {
+			t.Errorf("archive missing entry %q; got %v", name, names)
+		}
+	}
+}
+
+func tarEntryNames(t *testing.T, archive []byte) map[string]bool {
+	t.Helper()
+	gzipReader, err := gzip.NewReader(bytes.NewReader(archive))
+	if err != nil {
+		t.Fatalf("gzip reader: %v", err)
+	}
+	defer gzipReader.Close()
+	tarReader := tar.NewReader(gzipReader)
+	names := map[string]bool{}
+	for {
+		header, err := tarReader.Next()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			t.Fatalf("tar next: %v", err)
+		}
+		names[filepath.ToSlash(filepath.Clean(header.Name))] = true
+	}
+	return names
+}