diff --git a/spec/wibox/widget/systray_spec.lua b/spec/wibox/widget/systray_spec.lua
new file mode 100644
index 000000000..e625d7f83
--- /dev/null
+++ b/spec/wibox/widget/systray_spec.lua
@@ -0,0 +1,87 @@
+---------------------------------------------------------------------------
+-- @author Uli Schlachter
+-- @copyright 2020 Uli Schlachter
+---------------------------------------------------------------------------
+
+local unpack = unpack or table.unpack -- luacheck: globals unpack (compatibility with Lua 5.1)
+
+local systray_widget = nil
+local drawable_mock = {
+    _set_systray_widget = function(widget)
+        assert(systray_widget == nil)
+        assert(widget ~= nil)
+        systray_widget = widget
+    end
+}
+local beautiful_mock = {}
+package.loaded["wibox.drawable"] = drawable_mock
+package.loaded.beautiful = beautiful_mock
+
+local num_systray_icons
+local systray_arguments
+_G.awesome = {
+    connect_signal = function() end,
+    systray = function(first_arg, ...)
+        if first_arg then
+            assert(systray_arguments == nil) -- May only be called once
+            systray_arguments = { first_arg, ... }
+        end
+        return num_systray_icons
+    end
+}
+_G.screen = {
+    connect_signal = function() end
+}
+
+local systray = require("wibox.widget.systray")
+
+require("wibox.test_utils") -- For assert.widget_fit
+require("wibox.widget.base").rect_to_device_geometry = function() return 0, 0, 0, 0 end
+
+describe("wibox.widget.systray", function()
+    local widget = nil
+    before_each(function()
+        widget = systray()
+        assert(widget == systray_widget)
+    end)
+
+    local context = { wibox = { drawin = true } }
+    local cr = { user_to_device_distance = function() return 1, 0 end }
+
+    local function test_systray(available_size, expected_size, expected_base)
+        systray_arguments = nil
+        assert.widget_fit(widget, available_size, expected_size)
+        widget:draw(context, cr, unpack(available_size))
+        assert(systray_arguments[4] == expected_base,
+            string.format("Got base size %s, but expected %s", systray_arguments[4], expected_base))
+        assert.is.same(systray_arguments, {true, 0, 0, expected_base, true, '#000000', false, 0})
+    end
+
+    describe("no spacing", function()
+        it("no icons", function()
+            num_systray_icons = 0
+            test_systray({ 100, 10 }, { 0, 0 }, 10)
+            test_systray({ 100, 100 }, { 0, 0 }, 100)
+        end)
+
+        it("one icon", function()
+            num_systray_icons = 1
+            test_systray({ 100, 10 }, { 10, 10 }, 10)
+            test_systray({ 100, 100 }, { 100, 100 }, 100)
+        end)
+
+        it("two icons", function()
+            num_systray_icons = 2
+            test_systray({ 100, 10 }, { 20, 10 }, 10)
+            test_systray({ 100, 100 }, { 100, 100 }, 100 / 2)
+        end)
+
+        it("three icons", function()
+            num_systray_icons = 3
+            test_systray({ 100, 10 }, { 30, 10 }, 10)
+            test_systray({ 100, 100 }, { 100, 100 }, 100 / 3)
+        end)
+    end)
+end)
+
+-- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80