test: expand unit coverage

internal/event/transport/coverage_edges_test.go

@@ -0,0 +1,82 @@
+//go:build !windows
+
+package transport
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"net"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestFrameCodecCoverageEdges(t *testing.T) {
+	if _, err := NewReader(strings.NewReader("partial")).Read(); !errors.Is(err, io.EOF) {
+		t.Fatalf("partial frame error = %v, want EOF", err)
+	}
+	if err := NewReader(strings.NewReader("")).ReadJSON(&map[string]any{}); !errors.Is(err, io.EOF) {
+		t.Fatalf("ReadJSON EOF = %v", err)
+	}
+	if err := NewWriter(io.Discard).WriteJSON(make(chan int)); err == nil {
+		t.Fatal("unsupported JSON value should fail")
+	}
+}
+
+func TestUnixListenErrorCoverage(t *testing.T) {
+	oldStat, oldRemove, oldListen, oldChmod := statSocket, removeSocket, listenUnix, chmodSocket
+	t.Cleanup(func() {
+		statSocket, removeSocket, listenUnix, chmodSocket = oldStat, oldRemove, oldListen, oldChmod
+	})
+	wantErr := errors.New("synthetic failure")
+	path := filepath.Join(t.TempDir(), "bus.sock")
+	if _, err := listen(strings.Repeat("x", 512)); err == nil {
+		t.Fatal("overlong socket path should fail")
+	}
+
+	statSocket = func(string) (os.FileInfo, error) { return nil, nil }
+	removeSocket = func(string) error { return wantErr }
+	if _, err := listen(path); !errors.Is(err, wantErr) {
+		t.Fatalf("stale remove error = %v", err)
+	}
+
+	statSocket = func(string) (os.FileInfo, error) { return nil, os.ErrNotExist }
+	listenUnix = func(string, string) (net.Listener, error) { return nil, wantErr }
+	if _, err := listen(path); !errors.Is(err, wantErr) {
+		t.Fatalf("listen error = %v", err)
+	}
+
+	closed := false
+	listener := &stubNetListener{close: func() error { closed = true; return nil }}
+	listenUnix = func(string, string) (net.Listener, error) { return listener, nil }
+	chmodSocket = func(string, os.FileMode) error { return wantErr }
+	removeSocket = func(string) error { return nil }
+	if _, err := listen(path); !errors.Is(err, wantErr) || !closed {
+		t.Fatalf("chmod error = %v, closed=%v", err, closed)
+	}
+
+	removeSocket = func(string) error { return wantErr }
+	if err := (&unixListener{l: listener, path: path}).Close(); err != nil {
+		t.Fatalf("listener close should ignore unlink error: %v", err)
+	}
+
+	var buf bytes.Buffer
+	if err := NewWriter(&buf).WriteJSON(map[string]any{"ok": true}); err != nil {
+		t.Fatalf("sanity frame write: %v", err)
+	}
+}
+
+type stubNetListener struct {
+	close func() error
+}
+
+func (*stubNetListener) Accept() (net.Conn, error) { return nil, io.EOF }
+func (l *stubNetListener) Close() error            { return l.close() }
+func (*stubNetListener) Addr() net.Addr            { return stubNetAddr{} }
+
+type stubNetAddr struct{}
+
+func (stubNetAddr) Network() string { return "unix" }
+func (stubNetAddr) String() string  { return "stub" }