Make pt-stalk/pt-stalk.t stable. Add PerconaTest::not_running().

lib/PerconaTest.pm

@@ -222,7 +222,7 @@ sub parse_file {
 # Wait until code returns true.
 sub wait_until {
    my ( $code, $t, $max_t ) = @_;
-   $t     ||= .25;
+   $t     ||= .20;
    $max_t ||= 5;
 
    my $slept = 0;
@@ -306,6 +306,19 @@ sub wait_for_sh {
    );
 };
 
+sub not_running {
+   my ($cmd) = @_;
+   PTDEVDEBUG && _d('Wait until not running:', $cmd);
+   return wait_until(
+      sub {
+         my $output = `ps x | grep -v grep | grep "$cmd"`;
+         PTDEVDEBUG && _d($output);
+         return 1 unless $output;
+         return 0;
+      }
+   );
+}
+
 sub _read {
    my ( $fh ) = @_;
    return <$fh>;

t/pt-stalk/pt-stalk.t

@@ -155,10 +155,8 @@ is(
    "Collect ran for --run-time"
 );
 
-$output = `ps x | grep -v grep | grep 'pt-stalk --iterations 1'`;
-is(
-   $output,
-   "",
+ok(
+   PerconaTest::not_running("pt-stalk --iterations 1"),
    "pt-stalk is not running"
 );
 
@@ -202,10 +200,8 @@ ok(
    "No files collected"
 );
 
-$output = `ps x | grep -v grep | grep 'pt-stalk --no-collect'`;
-is(
-   $output,
-   "",
+ok(
+   PerconaTest::not_running("pt-stalk --no-collect"),
    "pt-stalk is not running"
 );
 
@@ -280,10 +276,8 @@ is(
    "Not stalking, collect gathered data"
 );
 
-$output = `ps x | grep -v grep | grep 'pt-stalk --no-stalk'`;
-is(
-   $output,
-   "",
+ok(
+   PerconaTest::not_running("pt-stalk --no-stalk"),
    "Not stalking, pt-stalk is not running"
 );