comments and clarifications

pytest_pyodide/node_test_driver.js

@@ -55,13 +55,18 @@ rl.on("line", async function (line) {
     return;
   }
   if (line !== cur_uuid) {
+    // each line ends with an extra $, to avoid problems with end-of-line 
+    // translation etc.
     line = line.substring(0, line.lastIndexOf('$'))
     if(line === ""){
       cur_code += "\n";
     } else {
       cur_code += line;
     }
-    console.log("OK")
+    // tell runner.py that the line has been read
+    // so it can send the next line without worrying about 
+    // filling buffers
+    console.log("{LINE_OK}")
   } else {
     evalCode(cur_uuid, cur_code, context);
     cur_code = "";

pytest_pyodide/runner.py

@@ -607,20 +607,29 @@ def run_js_inner(self, code, check_code):
 
         cmd_id = str(uuid4())
         self.p.sendline(cmd_id)
-        # split lines into shorter buffers
+        # split long lines into shorter buffers
         # because some ttys don't like long
         # single lines
         all_lines = wrapped.split("\n")
         for c, line in enumerate(all_lines):
             count = 0
             while count < len(line):
                 to_read = min(128, len(line) - count)
+                # each sent line ends with an extra $, to avoid problems with end-of-line 
+                # translation etc. it doesn't matter if there are $ in the string elsewhere
+                # because the last $ is always the one we added
                 self.p.sendline(line[count : count + to_read] + "$")
-                self.p.expect_exact("OK\r\n")
+                # after we send a line, we wait for a response
+                # before sending the next line
+                # this means we don't overflow input buffers
+                self.p.expect_exact("{LINE_OK}\r\n")
                 count += to_read
             if c < len(all_lines) - 1:
+                # to insert a line break into the received code string
+                # we send a blank line with just the $ end-of-line character
+                # and await response
                 self.p.sendline("$")
-                self.p.expect_exact("OK\r\n")
+                self.p.expect_exact("{LINE_OK}\r\n")
         self.p.sendline(cmd_id)
         self.p.expect_exact(f"{cmd_id}:UUID\r\n", timeout=self.script_timeout)
         self.p.expect_exact(f"{cmd_id}:UUID\r\n")