diff --git a/tests/lua/test_afd.lua b/tests/lua/test_afd.lua
new file mode 100644
index 0000000..a54bdfd
--- /dev/null
+++ b/tests/lua/test_afd.lua
@@ -0,0 +1,155 @@
+-- Copyright 2015 Mirantis, Inc.
+--
+-- Licensed under the Apache License, Version 2.0 (the "License");
+-- you may not use this file except in compliance with the License.
+-- You may obtain a copy of the License at
+--
+--     http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS,
+-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+-- See the License for the specific language governing permissions and
+-- limitations under the License.
+
+EXPORT_ASSERT_TO_GLOBALS=true
+require('luaunit')
+package.path = package.path .. ";../heka/files/lua/common/?.lua;lua/mocks/?.lua"
+
+-- mock the inject_message() function from the Heka sandbox library
+local last_injected_msg
+function inject_message(msg)
+    last_injected_msg = msg
+end
+
+local afd = require('afd')
+local consts = require('gse_constants')
+local extra = require('extra_fields')
+
+TestAfd = {}
+
+    function TestAfd:setUp()
+        afd.reset_alarms()
+    end
+
+    function TestAfd:test_add_to_alarms()
+        afd.add_to_alarms(consts.CRIT, 'last', 'metric_1', {}, {}, '==', 0, 0, nil, nil, "crit message")
+        local alarms = afd.get_alarms()
+        assertEquals(alarms[1].severity, 'CRITICAL')
+        assertEquals(alarms[1].metric, 'metric_1')
+        assertEquals(alarms[1].message, 'crit message')
+
+        afd.add_to_alarms(consts.WARN, 'last', 'metric_2', {}, {}, '>=', 10, 2, 5, 600, "warn message")
+        alarms = afd.get_alarms()
+        assertEquals(alarms[2].severity, 'WARN')
+        assertEquals(alarms[2].metric, 'metric_2')
+        assertEquals(alarms[2].message, 'warn message')
+    end
+
+    function TestAfd:test_inject_afd_metric_without_alarms()
+        afd.inject_afd_metric(consts.OKAY, 'node-1', 'foo', {}, false)
+
+        local alarms = afd.get_alarms()
+        assertEquals(#alarms, 0)
+        assertEquals(last_injected_msg.Type, 'afd_metric')
+        assertEquals(last_injected_msg.Fields.value, consts.OKAY)
+        assertEquals(last_injected_msg.Fields.hostname, 'node-1')
+        assertEquals(last_injected_msg.Payload, '{"alarms":[]}')
+    end
+
+    function TestAfd:test_inject_afd_metric_with_alarms()
+        afd.add_to_alarms(consts.CRIT, 'last', 'metric_1', {}, {}, '==', 0, 0, nil, nil, "important message")
+        afd.inject_afd_metric(consts.CRIT, 'node-1', 'foo', {}, false)
+
+        local alarms = afd.get_alarms()
+        assertEquals(#alarms, 0)
+        assertEquals(last_injected_msg.Type, 'afd_metric')
+        assertEquals(last_injected_msg.Fields.value, consts.CRIT)
+        assertEquals(last_injected_msg.Fields.hostname, 'node-1')
+        assertEquals(last_injected_msg.Fields.environment_id, extra.environment_id)
+        assert(last_injected_msg.Payload:match('"message":"important message"'))
+        assert(last_injected_msg.Payload:match('"severity":"CRITICAL"'))
+    end
+
+    function TestAfd:test_alarms_for_human_without_fields()
+        local alarms = afd.alarms_for_human({{
+            severity='WARNING',
+            ['function']='avg',
+            metric='load_longterm',
+            fields={},
+            tags={},
+            operator='>',
+            value=7,
+            threshold=5,
+            window=600,
+            periods=0,
+            message='load too high',
+        }})
+
+        assertEquals(#alarms, 1)
+        assertEquals(alarms[1], 'load too high (WARNING, rule=\'avg(load_longterm)>5\', current=7.00)')
+    end
+
+    function TestAfd:test_alarms_for_human_with_fields()
+        local alarms = afd.alarms_for_human({{
+            severity='CRITICAL',
+            ['function']='avg',
+            metric='fs_space_percent_free',
+            fields={fs='/'},
+            tags={},
+            operator='<=',
+            value=2,
+            threshold=5,
+            window=600,
+            periods=0,
+            message='free disk space too low'
+        }})
+
+        assertEquals(#alarms, 1)
+        assertEquals(alarms[1], 'free disk space too low (CRITICAL, rule=\'avg(fs_space_percent_free[fs="/"])<=5\', current=2.00)')
+    end
+
+    function TestAfd:test_alarms_for_human_with_hostname()
+        local alarms = afd.alarms_for_human({{
+            severity='WARNING',
+            ['function']='avg',
+            metric='load_longterm',
+            fields={},
+            tags={},
+            operator='>',
+            value=7,
+            threshold=5,
+            window=600,
+            periods=0,
+            message='load too high',
+            hostname='node-1'
+        }})
+
+        assertEquals(#alarms, 1)
+        assertEquals(alarms[1], 'load too high (WARNING, rule=\'avg(load_longterm)>5\', current=7.00, host=node-1)')
+    end
+
+    function TestAfd:test_alarms_for_human_with_hints()
+        local alarms = afd.alarms_for_human({{
+            severity='WARNING',
+            ['function']='avg',
+            metric='load_longterm',
+            fields={},
+            tags={dependency_level='hint',dependency_name='controller'},
+            operator='>',
+            value=7,
+            threshold=5,
+            window=600,
+            periods=0,
+            message='load too high',
+            hostname='node-1'
+        }})
+
+        assertEquals(#alarms, 2)
+        assertEquals(alarms[1], 'Other related alarms:')
+        assertEquals(alarms[2], 'load too high (WARNING, rule=\'avg(load_longterm)>5\', current=7.00, host=node-1)')
+    end
+
+lu = LuaUnit
+lu:setVerbosity( 1 )
+os.exit( lu:run() )