SERVER-48951: Add usability options for resmoke output.

--mrlog will pipe all stdout through mrlog.

--userFriendlyOutput=<file> will `tee` all output to <file>. It will filter
stdout with a grep to highlight test progress and possible failures.

1 files changed, 58 insertions, 0 deletions

diff --git a/buildscripts/tests/resmokelib/core/test_redirect.py b/buildscripts/tests/resmokelib/core/test_redirect.py
new file mode 100644
index 00000000000..44a1b83d10e
--- /dev/null
+++ b/buildscripts/tests/resmokelib/core/test_redirect.py
@@ -0,0 +1,58 @@
+"""Unit tests for buildscripts/resmokelib/core/redirect.py."""
+
+from __future__ import absolute_import
+
+import io
+import os
+import subprocess
+import tempfile
+import unittest
+
+from buildscripts.resmokelib.core import redirect as _redirect
+
+# pylint: disable=missing-docstring
+
+
+class TestStdoutRedirect(unittest.TestCase):
+    is_windows = os.name == "nt"
+
+    def test_process_pipes(self):
+        """Write a string, one word per line into the beginning of a chain of processes. The input
+        will be tee'd into a temporary file and grepped. Verify the contents of the tee'd file and
+        the final output of the grep.
+        """
+
+        if self.is_windows:
+            return
+
+        haystack = "can you find a needle in a haystack".split()
+        tmp_file = tempfile.mktemp()
+
+        try:
+            tee = _redirect.Pipe(["tee", tmp_file], subprocess.PIPE, subprocess.PIPE)
+            grep = _redirect.Pipe(["grep", "needle"], tee.get_stdout(), subprocess.PIPE)
+
+            for word in haystack:
+                # Write the message with a newline after each word. Grep should only match "needle".
+                tee.proc.stdin.write((word + "\n").encode("utf-8"))
+
+            tee.get_stdin().close()
+            self.assertEqual(b"needle", grep.get_stdout().read().strip())
+
+            with open(tmp_file) as teed_file:
+                self.assertEqual("\n".join(haystack) + "\n", teed_file.read())
+        finally:
+            tee.wait()
+            grep.wait()
+            tee.get_stdout().close()
+            grep.get_stdout().close()
+            os.remove(tmp_file)
+
+    def test_stdout_rewrite(self):
+        string = "mary had a little lamb"
+        acc = io.BytesIO()
+        with _redirect.StdoutRewrite(acc):
+            print(string)
+
+        print("not to be captured")
+        self.assertEqual(string + "\n", acc.getvalue().decode("utf-8"))