[OE-core] [PATCH 1/2] oeqa.utils.commands: limit runCmd exception output

[Markus Lehtonen]

Make it possible to limit the length of output lines shown in runCmd
exceptions. E.g when running bitbake we easily get thousands of lines of
log output, where only the last few (tens) are interesting or relevant
when an error occurs.

Signed-off-by: Markus Lehtonen <markus.lehtonen at linux.intel.com>
---
 meta/lib/oeqa/utils/commands.py | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/meta/lib/oeqa/utils/commands.py b/meta/lib/oeqa/utils/commands.py
index 82c5908..6901f1a 100644
--- a/meta/lib/oeqa/utils/commands.py
+++ b/meta/lib/oeqa/utils/commands.py
@@ -97,7 +97,8 @@ class Result(object):
     pass
 
 
-def runCmd(command, ignore_status=False, timeout=None, assert_error=True, native_sysroot=None, **options):
+def runCmd(command, ignore_status=False, timeout=None, assert_error=True,
+          native_sysroot=None, limit_exc_output=0, **options):
     result = Result()
 
     if native_sysroot:
@@ -117,10 +118,16 @@ def runCmd(command, ignore_status=False, timeout=None, assert_error=True, native
     result.pid = cmd.process.pid
 
     if result.status and not ignore_status:
+        exc_output = result.output
+        if limit_exc_output > 0:
+            split = result.output.splitlines()
+            if len(split) > limit_exc_output:
+                exc_output = "\n... (last %d lines of output)\n" % limit_exc_output + \
+                             '\n'.join(split[-limit_exc_output:])
         if assert_error:
-            raise AssertionError("Command '%s' returned non-zero exit status %d:\n%s" % (command, result.status, result.output))
+            raise AssertionError("Command '%s' returned non-zero exit status %d:\n%s" % (command, result.status, exc_output))
         else:
-            raise CommandError(result.status, command, result.output)
+            raise CommandError(result.status, command, exc_output)
 
     return result
 
-- 
2.10.2