add a length test for logger testcase to exercise the boundary between reused vs. fresh buffer

ecmascript-testcases/test-bi-logger.js

@@ -6,12 +6,15 @@
  *  log lines to write expect strings.
  */
 
-Duktape.Logger.prototype.raw = function raw_replacement(msg) {
+function raw_replacement(msg) {
     // Timestamp is non-predictable
+    msg = String(msg);  // arg is a buffer
     msg = msg.replace(/^\S+/, 'TIMESTAMP');
     print(msg);
 }
 
+Duktape.Logger.prototype.raw = raw_replacement;
+
 /*===
 logger name
 TIMESTAMP INF myLogger: logger created
@@ -79,7 +82,7 @@ print('logger name');
 try {
     loggerNameTest();
 } catch (e) {
-    print(e);
+    print(e.stack);
 }
 
 /*===
@@ -310,3 +313,172 @@ try {
 } catch (e) {
     print(e);
 }
+
+/*===
+length test
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+===*/
+
+/* There are internal behavior differences when logging short and long
+ * log messages.  Short messages (currently) reuse a single stashed
+ * buffer, while longer messages use one-off buffers.  Exercise the
+ * boundary between the two.  The limit is DUK_BI_LOGGER_SHORT_MSG_LIMIT,
+ * currently 256.
+ */
+
+function lengthTest() {
+    var logger;
+    var msg;
+
+    // Replace raw() with something that just prints the result length.
+
+    function raw_printlen(msg) {
+        print(String(msg).length);
+    }
+    Duktape.Logger.prototype.raw = raw_printlen;
+
+    function mkStr(len) {
+        var res = '';
+        while (len--) {
+            res = res + 'x';
+        }
+        return res;
+    }
+
+    // Exercise the boundary between the two buffer behaviors.  Start earlier
+    // than the limit to account for the log prefix.
+    logger = new Duktape.Logger('myLogger');
+    msg = mkStr(200);
+    while (msg.length <= 290) {
+        logger.info(msg);
+        msg = msg + 'x';
+    }
+
+    // Test log entries up to 1 MB.
+    msg = 'y';
+    while (msg.length <= 1024 * 1024) {
+        logger.info(msg);
+        msg = msg + msg;
+    }
+}
+
+print('length test');
+
+try {
+    lengthTest();
+} catch (e) {
+    print(e);
+}
+
+Duktape.Logger.prototype.raw = raw_replacement;