diff --git a/test/.gitignore b/test/.gitignore
new file mode 100644
index 0000000..da223b4
--- /dev/null
+++ b/test/.gitignore
@@ -0,0 +1 @@
+/negent-test.log
diff --git a/test/fuzz.pl b/test/fuzz.pl
new file mode 100755
index 0000000..14ea445
--- /dev/null
+++ b/test/fuzz.pl
@@ -0,0 +1,112 @@
+#!/usr/bin/env perl
+
+use strict;
+
+use IPC::Open2;
+use Session::Token;
+
+my $harnessType = shift || die "please provide harness type (cpp, js, etc)";
+my $idSize = shift || 16;
+
+
+my $harnessCmd;
+
+if ($harnessType eq 'cpp') {
+    $harnessCmd = './cpp/harness';
+} elsif ($harnessType eq 'js') {
+    $harnessCmd = 'node js/harness.js';
+} else {
+    die "unknown harness type: $harnessType";
+}
+
+
+srand($ENV{SEED} || 0);
+my $stgen = Session::Token->new(seed => "\x00" x 1024, alphabet => '0123456789abcdef', length => $idSize * 2);
+
+
+my $iters = $ENV{ITERS} // 1;
+
+my $minRecs = $ENV{MIN_RECS} // 1;
+my $maxRecs = $ENV{MAX_RECS} // 10_000;
+die "MIN_RECS > MAX_RECS" if $minRecs > $maxRecs;
+$minRecs = $maxRecs = $ENV{RECS} if $ENV{RECS};
+
+my $prob1 = $ENV{P1} // 1;
+my $prob2 = $ENV{P2} // 1;
+my $prob3 = $ENV{P3} // 98;
+
+{
+    my $total = $prob1 + $prob2 + $prob3;
+    die "zero prob" if $total == 0;
+    $prob1 = $prob1 / $total;
+    $prob2 = $prob2 / $total;
+    $prob3 = $prob3 / $total;
+}
+
+
+for (my $i = 0; $i < $iters; $i++) {
+    my $ids1 = {};
+    my $ids2 = {};
+
+    my $pid = open2(my $outfile, my $infile, $harnessCmd);
+
+    my $num = $minRecs + rnd($maxRecs - $minRecs);
+
+    for (1..$num) {
+        my $mode;
+
+        my $modeRnd = rand();
+
+        if ($modeRnd < $prob1) {
+            $mode = 1;
+        } elsif ($modeRnd < $prob1 + $prob2) {
+            $mode = 2;
+        } else {
+            $mode = 3;
+        }
+
+        my $created = 1677970534 + rnd($num);
+        my $id = $stgen->get;
+
+        $ids1->{$id} = 1 if $mode == 1 || $mode == 3;
+        $ids2->{$id} = 1 if $mode == 2 || $mode == 3;
+
+        print $infile "$mode,$created,$id\n";
+    }
+
+    close($infile);
+
+    while (<$outfile>) {
+        if (/^xor,(HAVE|NEED),(\w+)/) {
+            my ($action, $id) = ($1, $2);
+
+            if ($action eq 'NEED') {
+                die "duplicate insert of $action,$id" if $ids1->{$id};
+                $ids1->{$id} = 1;
+            } elsif ($action eq 'HAVE') {
+                die "duplicate insert of $action,$id" if $ids2->{$id};
+                $ids2->{$id} = 1;
+            }
+        }
+    }
+
+    waitpid($pid, 0);
+    my $child_exit_status = $?;
+    die "failure running test harness" if $child_exit_status;
+
+    for my $id (keys %$ids1) {
+        die "$id not in ids2" if !$ids2->{$id};
+    }
+
+    for my $id (keys %$ids2) {
+        die "$id not in ids1" if !$ids1->{$id};
+    }
+
+    print "\n-----------OK-----------\n";
+}
+
+
+sub rnd {
+    my $n = shift;
+    return int(rand() * $n);
+}
diff --git a/test/test.pl b/test/test.pl
index 92761f1..1640836 100755
--- a/test/test.pl
+++ b/test/test.pl
@@ -1,87 +1,42 @@
 #!/usr/bin/env perl
 
-use IPC::Open2;
-use Session::Token;
+use strict;
 
-my $harnessType = shift || die "please provide harness type (cpp, js, etc)";
-my $idSize = shift || 16;
+unlink("negent-test.log");
 
 
-my $harnessCmd;
+note("Full upload");
+run("RECS=100000 FRAMESIZELIMIT1=60000 FRAMESIZELIMIT2=500000 P1=1 P2=0 P3=0 perl fuzz.pl cpp");
 
-if ($harnessType eq 'cpp') {
-    $harnessCmd = './cpp/harness';
-} elsif ($harnessType eq 'js') {
-    $harnessCmd = 'node js/harness.js';
-} else {
-    die "unknown harness type: $harnessType";
+note("Full download");
+run("RECS=100000 FRAMESIZELIMIT1=60000 FRAMESIZELIMIT2=500000 P1=0 P2=1 P3=0 perl fuzz.pl cpp");
+
+note("Identical DBs");
+run("RECS=100000 FRAMESIZELIMIT1=60000 FRAMESIZELIMIT2=500000 P1=0 P2=0 P3=1 perl fuzz.pl cpp");
+
+note("Mixed");
+run("RECS=100000 FRAMESIZELIMIT1=60000 FRAMESIZELIMIT2=500000 P1=1 P2=1 P3=5 perl fuzz.pl cpp");
+
+
+
+
+
+########
+
+sub run {
+    my $cmd = shift;
+
+    print "RUN: $cmd\n";
+
+    system("echo 'RUN: $cmd' >>negent-test.log");
+    system("$cmd >>negent-test.log 2>&1") && die "test failure";
+    system("echo '----------' >>negent-test.log");
 }
 
+sub note {
+    my $note = shift;
 
-srand($ENV{SEED} || 0);
-my $stgen = Session::Token->new(seed => "\x00" x 1024, alphabet => '0123456789abcdef', length => $idSize * 2);
+    print "NOTE: $note\n";
 
-
-my $iters = $ENV{ITERS} || 100;
-
-for (my $i = 0; $i < $iters; $i++) {
-    my $ids1 = {};
-    my $ids2 = {};
-
-    my $pid = open2(my $outfile, my $infile, $harnessCmd);
-
-    my $num = rnd(10000) + 1;
-
-    for (1..$num) {
-        my $mode;
-        if (rand() < .01) {
-            $mode = rnd(2) + 1;
-        } else {
-            $mode = 3;
-        }
-
-        my $created = 1677970534 + rnd($num);
-        my $id = $stgen->get;
-
-        $ids1->{$id} = 1 if $mode == 1 || $mode == 3;
-        $ids2->{$id} = 1 if $mode == 2 || $mode == 3;
-
-        print $infile "$mode,$created,$id\n";
-    }
-
-    close($infile);
-
-    while (<$outfile>) {
-        if (/^xor,(HAVE|NEED),(\w+)/) {
-            my ($action, $id) = ($1, $2);
-
-            if ($action eq 'NEED') {
-                die "duplicate insert of $action,$id" if $ids1->{$id};
-                $ids1->{$id} = 1;
-            } elsif ($action eq 'HAVE') {
-                die "duplicate insert of $action,$id" if $ids2->{$id};
-                $ids2->{$id} = 1;
-            }
-        }
-    }
-
-    waitpid($pid, 0);
-    my $child_exit_status = $?;
-    die "failure running test harness" if $child_exit_status;
-
-    for my $id (keys %$ids1) {
-        die "$id not in ids2" if !$ids2->{$id};
-    }
-
-    for my $id (keys %$ids2) {
-        die "$id not in ids1" if !$ids1->{$id};
-    }
-
-    print "\n-----------OK-----------\n";
-}
-
-
-sub rnd {
-    my $n = shift;
-    return int(rand() * $n);
+    system("echo 'NOTE: $note' >>negent-test.log");
 }