Add check max refs for body

src/boc/Cell.js

@@ -21,6 +21,27 @@ class Cell {
         this.isExotic = false;
     }
 
+    /**
+     * @return {number}
+     */
+    get max_refs() {
+        return 4;
+    }
+
+    /**
+     * @return {number}
+     */
+    getFreeRefs() {
+        return this.max_refs - this.refs.length;
+    }
+
+    /**
+     * @return {number}
+     */
+    getUsedRefs() {
+        return this.refs.length;
+    }
+
     /**
      * @param serializedBoc  {string | Uint8Array} hex or bytearray
      * @return {Cell[]} root cells

src/contract/index.js

@@ -197,9 +197,12 @@ class Contract {
         } else {
             commonMsgInfo.bits.writeBit(false);
         }
-        // TODO we also should check for free refs here
+
         if (body) {
-            if (commonMsgInfo.bits.getFreeBits() >= body.bits.getUsedBits()) {
+            if (
+                commonMsgInfo.bits.getFreeBits() >= body.bits.getUsedBits() && 
+                commonMsgInfo.getFreeRefs() >= body.getUsedRefs()
+            ) {
                 commonMsgInfo.bits.writeBit(false);
                 commonMsgInfo.writeCell(body);
             } else {