Add connection management methods and tests for websocket client

Fixes #139

websocket/client_test.go

@@ -0,0 +1,113 @@
+package websocket
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/gorilla/websocket"
+)
+
+// newTestClient returns a bare Client suitable for exercising conn
+// bookkeeping directly, without dialing a real server. isDisconnected is set
+// so reconnect() performs its compare-and-clear but never spawns a
+// connectWithRetry goroutine.
+func newTestClient() *Client {
+	return &Client{
+		done:           make(chan struct{}),
+		isDisconnected: true,
+	}
+}
+
+// dialTestConn spins up a throwaway websocket server and returns a live
+// client-side *websocket.Conn, for tests that need a real connection (i.e.
+// one that survives a Close() call without panicking).
+func dialTestConn(t *testing.T) *websocket.Conn {
+	t.Helper()
+	upgrader := websocket.Upgrader{}
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		conn, err := upgrader.Upgrade(w, r, nil)
+		if err != nil {
+			return
+		}
+		defer conn.Close()
+		select {}
+	}))
+	t.Cleanup(srv.Close)
+
+	wsURL := "ws" + strings.TrimPrefix(srv.URL, "http")
+	conn, _, err := websocket.DefaultDialer.Dial(wsURL, nil)
+	if err != nil {
+		t.Fatalf("failed to dial test server: %v", err)
+	}
+	t.Cleanup(func() { conn.Close() })
+	return conn
+}
+
+func TestClearConnIfCurrentClearsMatchingConnection(t *testing.T) {
+	c := newTestClient()
+	a := dialTestConn(t)
+	c.setConn(a)
+
+	if !c.clearConnIfCurrent(a) {
+		t.Fatal("expected clearConnIfCurrent(a) to succeed when a is the active connection")
+	}
+	if got := c.getConn(); got != nil {
+		t.Fatalf("expected conn to be nil after clearing, got %v", got)
+	}
+}
+
+func TestClearConnIfCurrentIgnoresStaleConnection(t *testing.T) {
+	c := newTestClient()
+	a := dialTestConn(t)
+	b := dialTestConn(t)
+	c.setConn(a)
+
+	// Simulate a concurrent winner already having replaced a with b.
+	c.setConn(b)
+
+	if c.clearConnIfCurrent(a) {
+		t.Fatal("expected clearConnIfCurrent(a) to fail once b has replaced a as the active connection")
+	}
+	if got := c.getConn(); got != b {
+		t.Fatalf("stale clearConnIfCurrent(a) must not clobber the newer connection: got %v, want %v", got, b)
+	}
+}
+
+// TestReconnectIgnoresStaleConnection is the direct regression test for
+// fosrl/olm#139: the read pump and sendPing can both react to the same dead
+// connection and call reconnect() independently. Once one of them has
+// already replaced c.conn with a newer connection, the other's reconnect
+// call (carrying the old, now-stale connection) must be a no-op rather than
+// tearing down or nulling out the newer connection out from under its own
+// read pump.
+func TestReconnectIgnoresStaleConnection(t *testing.T) {
+	c := newTestClient()
+	a := dialTestConn(t)
+	b := dialTestConn(t)
+	c.setConn(a)
+
+	// A winning concurrent reconnect already replaced a with b.
+	c.setConn(b)
+
+	// The stale report for `a` must not touch b, and must not attempt to
+	// close `a` a second time or otherwise panic.
+	c.reconnect(a)
+
+	if got := c.getConn(); got != b {
+		t.Fatalf("stale reconnect(a) must not clobber the newer connection: got %v, want %v", got, b)
+	}
+}
+
+func TestReconnectClearsCurrentConnection(t *testing.T) {
+	c := newTestClient()
+	a := dialTestConn(t)
+	c.setConn(a)
+
+	c.reconnect(a)
+
+	if got := c.getConn(); got != nil {
+		t.Fatalf("expected conn to be cleared after reconnect(a) when a was still current, got %v", got)
+	}
+}