[Test] Add tests for pct=0 case

src/plugins/lua/dmarc.lua

@@ -415,12 +415,15 @@ local function dmarc_validate_policy(task, policy, hdrfromdom, dmarc_esld)
           policy.domain .. ' : ' .. reason_str, policy.dmarc_policy)
       disposition = what
     else
-      if (math.random(100) > policy.pct) then
+      local coin = math.random(100)
+      if (coin > policy.pct) then
         if (not no_sampling_domains or
             not no_sampling_domains:get_key(policy.domain)) then
           task:insert_result(dmarc_symbols['softfail'], 1.0,
               policy.domain .. ' : ' .. reason_str, policy.dmarc_policy, "sampled_out")
           sampled_out = true
+          lua_util.debugm(N, task, 'changed dmarc policy from %s to %s, sampled out: %s < %s',
+              what, 'softfail', coin, policy.pct)
         else
           task:insert_result(dmarc_symbols[what], 1.0,
               policy.domain .. ' : ' .. reason_str, policy.dmarc_policy, "local_policy")

test/functional/cases/115_dmarc.robot

@@ -77,6 +77,11 @@ DMARC NA NXDOMAIN
   ...  -i  37.48.67.26  --from  foo@mom.za.org
   Check Rspamc  ${result}  DMARC_NA
 
+DMARC PCT ZERO
+  ${result} =  Scan Message With Rspamc  ${TESTDIR}/messages/dmarc/pct_none.eml
+  ...  -i  37.48.67.26  --from  foo@mom.za.org
+  Check Rspamc  ${result}  DMARC_POLICY_SOFTFAIL
+
 DKIM PERMFAIL NXDOMAIN
   ${result} =  Scan Message With Rspamc  ${TESTDIR}/messages/dmarc/bad_dkim2.eml
   ...  -i  37.48.67.26

test/functional/configs/plugins.conf

@@ -242,6 +242,11 @@ options = {
           type = "txt";
           rcode = 'nxdomain';
         },
+        {
+          name = "_dmarc.zero_pct.com",
+          type = "txt";
+          replies = ["v=DMARC1; p=reject; sp=quarantine; pct=0"];
+        },
         {
           name = "example.com",
           type = "txt";

test/functional/messages/dmarc/pct_none.eml

@@ -0,0 +1,17 @@
+Date: Tue, 09 Aug 2016 10:01:27 +0200
+Message-ID: <20160809100128@rspamd.tk>
+From: Rspamd <foo@zero_pct.com>
+To: foo@rspamd.tk
+Subject: hello
+Content-Type: text/plain; charset=utf-8; format=flowed; DelSp=Yes
+MIME-Version: 1.0
+Content-Disposition: inline
+DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=rspamd.tk; s=testdkim;
+	t=1470729879; h=from:subject:date:message-id:to:mime-version:content-type;
+	bh=7HkRgYnNru3SR2EWfgWU8yhM0MOH6ZZrPoEIgNIh8wc=;
+	b=kTIV4jcgv9sWFh2JFrS/+PcNxiloituqjmHHqeJOTfa+/9C+Er8BjnMysTJyYVq36Gnv0OZDgLr3Yy4YP5Lzbt1M9ZdN5cJqO7yn1N7wyaGfkt++b09rIYBy5Dkk7OWyP3cDThqDzv8C9heSvqBSEsirFsbt3Wx2g/hWiJlnjew=
+
+
+hello
+
+