test(coverage): raise engine+agent coverage above 50%

internal/agent/disk_test.go

@@ -0,0 +1,62 @@
+package agent
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestDirSize(t *testing.T) {
+	root := t.TempDir()
+	if err := os.WriteFile(filepath.Join(root, "a.bin"), make([]byte, 100), 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.MkdirAll(filepath.Join(root, "sub"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(filepath.Join(root, "sub", "b.bin"), make([]byte, 250), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := DirSize(root)
+	if err != nil {
+		t.Fatalf("DirSize error: %v", err)
+	}
+	if got != 350 {
+		t.Errorf("DirSize = %d, want 350", got)
+	}
+}
+
+func TestDirSizeEmpty(t *testing.T) {
+	got, err := DirSize(t.TempDir())
+	if err != nil {
+		t.Fatalf("DirSize empty dir error: %v", err)
+	}
+	if got != 0 {
+		t.Errorf("DirSize empty = %d, want 0", got)
+	}
+}
+
+func TestDirSizeMissing(t *testing.T) {
+	// Walk skips unreadable entries — missing path returns 0 with no error.
+	got, err := DirSize("/nonexistent/path/zzz")
+	if err != nil {
+		t.Errorf("DirSize on missing path = err %v, want nil", err)
+	}
+	if got != 0 {
+		t.Errorf("DirSize on missing path = %d, want 0", got)
+	}
+}
+
+func TestDiskInfoCurrentDir(t *testing.T) {
+	free, total, err := DiskInfo(".")
+	if err != nil {
+		t.Fatalf("DiskInfo: %v", err)
+	}
+	if total <= 0 {
+		t.Errorf("total bytes should be > 0, got %d", total)
+	}
+	if free > total {
+		t.Errorf("free (%d) should not exceed total (%d)", free, total)
+	}
+}