Test API listener split and pipe URL forms

Cover the per-platform refactor of setupUnixSocket. On all
platforms, assert socketURL emits unix:// for filesystem
addresses and that isNamedPipeAddress detects \.\pipe\
prefixes. On Windows, additionally assert socketURL emits
npipe://<name>, that setupUnixSocket against a unique pipe
path returns a winio listener that accepts a winio dial within
a 2 s timeout (proving the listener is wired to the named-pipe
namespace, not AF_UNIX), and that cleanupUnixSocket no-ops for
pipe addresses without panicking.

Tests are split via build tags so the Windows test file is
only compiled on GOOS=windows and pulls in winio there.

Author: samuv

pkg/api/socket_other_test.go

@@ -0,0 +1,36 @@
+// SPDX-FileCopyrightText: Copyright 2025 Stacklok, Inc.
+// SPDX-License-Identifier: Apache-2.0
+
+//go:build !windows
+
+package api
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestSocketURL_Unix(t *testing.T) {
+	t.Parallel()
+	assert.Equal(t, "unix:///tmp/test.sock", socketURL("/tmp/test.sock"))
+}
+
+func TestIsNamedPipeAddress(t *testing.T) {
+	t.Parallel()
+	tests := []struct {
+		name    string
+		address string
+		want    bool
+	}{
+		{"plain socket", "/tmp/thv.sock", false},
+		{"named pipe", `\\.\pipe\thv-api`, true},
+		{"empty", "", false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			assert.Equal(t, tt.want, isNamedPipeAddress(tt.address))
+		})
+	}
+}

pkg/api/socket_windows_test.go

@@ -0,0 +1,89 @@
+// SPDX-FileCopyrightText: Copyright 2025 Stacklok, Inc.
+// SPDX-License-Identifier: Apache-2.0
+
+//go:build windows
+
+package api
+
+import (
+	"context"
+	"fmt"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/Microsoft/go-winio"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// pipeNameSeq disambiguates concurrent test pipes so parallel runs don't
+// collide on the global Windows pipe namespace.
+var pipeNameSeq atomic.Uint64
+
+func uniqueTestPipe() string {
+	return fmt.Sprintf(`\\.\pipe\thv-api-test-%d`, pipeNameSeq.Add(1))
+}
+
+func TestSocketURL_Windows(t *testing.T) {
+	t.Parallel()
+	tests := []struct {
+		name    string
+		address string
+		want    string
+	}{
+		{"named pipe", `\\.\pipe\thv-api`, "npipe://thv-api"},
+		{"af_unix windows path", `C:\path\thv.sock`, `unix://C:\path\thv.sock`},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+			assert.Equal(t, tt.want, socketURL(tt.address))
+		})
+	}
+}
+
+func TestSetupUnixSocket_NamedPipe(t *testing.T) {
+	t.Parallel()
+	pipePath := uniqueTestPipe()
+
+	listener, err := setupUnixSocket(pipePath)
+	require.NoError(t, err)
+	t.Cleanup(func() { _ = listener.Close() })
+
+	// The listener should accept a winio dial within a short timeout, proving
+	// it is wired to the named-pipe namespace and not to AF_UNIX.
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+
+	connCh := make(chan error, 1)
+	go func() {
+		conn, dialErr := winio.DialPipeContext(ctx, pipePath)
+		if conn != nil {
+			_ = conn.Close()
+		}
+		connCh <- dialErr
+	}()
+
+	go func() {
+		conn, _ := listener.Accept()
+		if conn != nil {
+			_ = conn.Close()
+		}
+	}()
+
+	select {
+	case err := <-connCh:
+		require.NoError(t, err)
+	case <-ctx.Done():
+		t.Fatal("dial against named-pipe listener timed out")
+	}
+}
+
+func TestCleanupUnixSocket_NamedPipe_NoOp(t *testing.T) {
+	t.Parallel()
+	// Passing a pipe address to cleanup must not error or panic. There is no
+	// file to remove; the assertion here is simply that the call returns
+	// cleanly.
+	cleanupUnixSocket(`\\.\pipe\thv-api-cleanup-noop`)
+}