fix: account for user-provided file descriptors in Tree.printDotGraph

Co-authored-by: Amaan Qureshi <[email protected]>

src/parser.cc

@@ -274,7 +274,7 @@ Napi::Value Parser::SetLogger(const Napi::CallbackInfo &info) {
 
 Napi::Value Parser::PrintDotGraphs(const Napi::CallbackInfo &info) {
   bool should_print = true;
-  int32_t fd = fileno(stderr);
+  int fd = fileno(stderr);
 
   if (info.Length() > 0) {
     if (!info[0].IsBoolean()) {

src/tree.cc

@@ -231,7 +231,16 @@ Napi::Value Tree::GetEditedRange(const Napi::CallbackInfo &info) {
 }
 
 Napi::Value Tree::PrintDotGraph(const Napi::CallbackInfo &info) {
-  ts_tree_print_dot_graph(tree_, fileno(stderr));
+  int fd = fileno(stderr);
+
+  if (info.Length() > 0) {
+    if (!info[0].IsNumber()) {
+      throw TypeError::New(info.Env(), "First argument must be a number");
+    }
+    fd = info[0].As<Number>().Int32Value();
+  }
+
+  ts_tree_print_dot_graph(tree_, fd);
   return info.This();
 }
 

test/tree_test.js

@@ -562,6 +562,30 @@ describe("Tree", () => {
       assert.notDeepEqual(node1.firstChild, node2);
     });
   });
+
+  describe(".printDotGraph()", () => {
+    it("prints a dot graph to the output file", () => {
+      if (process.platform === "win32") {
+        return;
+      }
+
+      const tmp = require("tmp");
+      const debugGraphFile = tmp.fileSync({ postfix: ".dot" });
+      const tree = parser.parse("const zero = 0");
+      tree.printDotGraph(debugGraphFile.fd);
+
+      const fs = require('fs');
+      const logReader = fs.readFileSync(debugGraphFile.name, 'utf8').split('\n');
+      for (let line of logReader) {
+        const match = line.match(/error-cost: (\d+)/);
+        if (match) {
+          assert.equal(parseInt(match[1]), 0); // error-cost should always be 0
+        }
+      }
+
+      debugGraphFile.removeCallback();
+    });
+  });
 });
 
 function assertCursorState(cursor, params) {