fix: no expiration date means not outdated

We were using Time.at(expirationdate) even if it was nil which
led to using the Time.at(0). Instead an unset expirationdate
is meant to not expire the key at all.

Our tests did not catch this because the assertions were in
blocks that did not get run at all. (at least in the HKP
integration test).

lib/nickserver/hkp/key_info.rb

@@ -49,7 +49,7 @@ module Nickserver::Hkp
 
     def expirationdate
       expires = properties[4]
-      Time.at(expires.to_i)
+      expires && Time.at(expires.to_i)
     end
 
     def flags

test/integration/hkp_test.rb

@@ -33,7 +33,7 @@ class HkpTest < Minitest::Test
     stubbing_http do
       uid = 'leaping_lemur@leap.se'
       stub_sks_vindex_reponse(uid, status: 404)
-      assert_response_status_for_uid uid, 404
+      assert_nil response_for_uid(uid)
     end
   end
 
@@ -41,7 +41,7 @@ class HkpTest < Minitest::Test
     stubbing_http do
       uid = 'leaping_lemur@leap.se'
       stub_sks_vindex_reponse(uid, status: 200)
-      assert_response_status_for_uid uid, 404
+      assert_nil response_for_uid(uid)
     end
   end
 
@@ -51,12 +51,11 @@ class HkpTest < Minitest::Test
     stubbing_http do
       stub_sks_vindex_reponse(uid, body: file_content(:leap_vindex_result))
       stub_sks_get_reponse(key_id, body: file_content(:leap_public_key))
-      assert_response_for_uid(uid) do |response|
+      response = response_for_uid(uid)
       content = JSON.parse response.content
       assert_equal file_content(:leap_public_key), content['openpgp']
     end
   end
-  end
 
   def test_fetch_key_not_found
     uid    = 'cloudadmin@leap.se'
@@ -65,7 +64,7 @@ class HkpTest < Minitest::Test
     stubbing_http do
       stub_sks_vindex_reponse(uid, body: file_content(:leap_vindex_result))
       stub_sks_get_reponse(key_id, status: 404)
-      assert_response_status_for_uid uid, 404
+      assert_equal 404, response_for_uid(uid).status
     end
   end
 
@@ -74,30 +73,21 @@ class HkpTest < Minitest::Test
 
     stubbing_http do
       stub_sks_vindex_reponse(uid, body: file_content(:short_key_vindex_result))
-      assert_response_status_for_uid uid, 500
+      assert_equal 500, response_for_uid(uid).status
     end
   end
 
   protected
 
-  def assert_response_status_for_uid(uid, status)
-    assert_response_for_uid(uid) do |response|
-      assert_equal status, response.status
-    end
-  end
-
-  def assert_response_for_uid(uid)
-    Nickserver::Hkp::Source.new(adapter).query uid do |response|
-      yield response
-    end
+  def response_for_uid(uid)
+    Nickserver::Hkp::Source.new(adapter).query uid
   end
 
   def assert_key_info_for_uid(uid)
-    Nickserver::Hkp::Source.new(adapter).search uid do |status, keys|
+    status, keys = Nickserver::Hkp::Source.new(adapter).search uid
     assert_equal 200, status
     yield keys
   end
-  end
 
   def fetch_key_info(body_source, uid, &block)
     stubbing_http do