rpc: refactor read limit test

rpc/websocket_test.go

@@ -121,56 +121,49 @@ func TestWebsocketLargeRead(t *testing.T) {
 		srv     = newTestServer()
 		httpsrv = httptest.NewServer(srv.WebsocketHandler([]string{"*"}))
 		wsURL   = "ws:" + strings.TrimPrefix(httpsrv.URL, "http:")
+		buffer  = 64
 	)
 	defer srv.Stop()
 	defer httpsrv.Close()
 
-	testLimit := func(limit *int64) {
-		opts := []ClientOption{}
-		expLimit := int64(wsDefaultReadLimit)
-		if limit != nil && *limit >= 0 {
-			opts = append(opts, WithWebsocketMessageSizeLimit(*limit))
-			if *limit > 0 {
-				expLimit = *limit // 0 means infinite
-			}
+	for _, tt := range []struct {
+		size  int
+		limit int
+		err   bool
+	}{
+		{200, 200, false},                                       // Small, successful request and limit
+		{wsDefaultReadLimit + buffer, 0, false},                 // Large, successful request, infinite limit
+		{wsDefaultReadLimit + buffer, wsDefaultReadLimit, true}, // Large, failed request, finite limit
+	} {
+		func() {
+			if tt.limit != 0 {
+				// Some buffer is added to the limit to account for JSON encoding. It's
+				// skipped when the limit is zero since the intention is for the limit
+				// to be infinite.
+				tt.limit += buffer
 			}
+			opts := []ClientOption{WithWebsocketMessageSizeLimit(int64(tt.limit))}
 			client, err := DialOptions(context.Background(), wsURL, opts...)
 			if err != nil {
-			t.Fatalf("can't dial: %v", err)
+				t.Fatalf("failed to dial test server: %v", err)
 			}
 			defer client.Close()
-		// Remove some bytes for json encoding overhead.
-		underLimit := int(expLimit - 128)
-		overLimit := expLimit + 1
-		if expLimit == wsDefaultReadLimit {
-			// No point trying the full 32MB in tests. Just sanity-check that
-			// it's not obviously limited.
-			underLimit = 1024
-			overLimit = -1
-		}
+
 			var res string
-		// Check under limit
-		if err = client.Call(&res, "test_repeat", "A", underLimit); err != nil {
-			t.Fatalf("unexpected error with limit %d: %v", expLimit, err)
+			err = client.Call(&res, "test_repeat", "A", tt.size)
+			if tt.err && err == nil {
+				t.Fatalf("expected error, got none")
 			}
-		if len(res) != underLimit || strings.Count(res, "A") != underLimit {
+			if !tt.err {
+				if err != nil {
+					t.Fatalf("unexpected error with limit %d: %v", tt.limit, err)
+				}
+				if strings.Count(res, "A") != tt.size {
 					t.Fatal("incorrect data")
 				}
-		// Check over limit
-		if overLimit > 0 {
-			err = client.Call(&res, "test_repeat", "A", expLimit+1)
-			if err == nil || err != websocket.ErrReadLimit {
-				t.Fatalf("wrong error with limit %d: %v expecting %v", expLimit, err, websocket.ErrReadLimit)
 			}
+		}()
 	}
-	}
-	ptr := func(v int64) *int64 { return &v }
-
-	testLimit(ptr(-1)) // Should be ignored (use default)
-	testLimit(ptr(0))  // Should be ignored (use default)
-	testLimit(nil)     // Should be ignored (use default)
-	testLimit(ptr(200))
-	testLimit(ptr(wsDefaultReadLimit * 2))
 }
 
 func TestWebsocketPeerInfo(t *testing.T) {