[dpaste] Add tests

plugins/dpaste/tests/helper.fish

+set -l fish_tank /usr/local/share/fish-tank/tank.fish
+if not test -e $fish_tank
+  echo 'error: fish-tank is required to run these tests (https://github.com/terlar/fish-tank)'
+  exit 1
+end
+
+source $fish_tank

plugins/dpaste/tests/test_dpaste.fish

+#!/usr/bin/env fish
+
+function suite_dpaste
+  function setup
+    set -g __dpaste_expires_choises
+    source ../dpaste.fish
+    __dpaste_set_defaults
+  end
+
+  function test_dpaste_parse_expires
+    assert_equal text (__dpaste_parse_expires text)
+    assert_equal "https://dpaste.de/api/?format=url" $__dpaste_send_url
+    assert_equal text (__dpaste_parse_expires -t never text)
+    assert_equal "https://dpaste.de/api/?format=url&expires=never" $__dpaste_send_url
+    assert_equal text (__dpaste_parse_expires -t hour 3600)
+    assert_equal "https://dpaste.de/api/?format=url&expires=" $__dpaste_send_url
+  end
+end
+
+if not set -q tank_running
+  source (dirname (status -f))/helper.fish
+  tank_run
+end