test: make SessionOutput Promise tolerant

mmarchini · mmarchini · commit 82d28c5e268c · 2020-01-14T08:41:30.000-08:00
If a test case would use Promises for linesUntil, sometimes we would emit lines events while there was no listener attached to it. This commit changes SessionOutput to make it a little more resilient: now line events will only be emitted when the SessionOutput is waiting. When wait is called (via linesUntil, for example), it'll retrieve all lines (via line events) on the buffer until it reaches a line matching the regexp. If no lines match the regexp, we'll continue as before waiting for data from lldb and buffering it. PR-URL: #311 Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
diff --git a/test/common.js b/test/common.js
@@ -45,10 +45,13 @@ function SessionOutput(session, stream, timeout) {
   this.timeout = timeout || 10000;
   this.session = session;
 
-  stream.on('data', (data) => {
-    buf += data;
-
+  this.flush = function flush() {
     for (;;) {
+      // NOTE(mmarchini): don't emit line events while not waiting, otherwise
+      // we might miss something.
+      if (!this.waiting)
+        break
+
       let index = buf.indexOf('\n');
 
       if (index === -1)
@@ -62,6 +65,11 @@ function SessionOutput(session, stream, timeout) {
       else
         this.emit('line', line);
     }
+  }
+
+  stream.on('data', (data) => {
+    buf += data;
+    this.flush();
   });
 
   // Ignore errors
@@ -129,6 +137,7 @@ SessionOutput.prototype.wait = function wait(regexp, callback, allLines) {
   }, this.timeout).unref();
 
   this.on('line', onLine);
+  this.flush();
 };
 
 SessionOutput.prototype.waitBreak = function waitBreak(callback) {
