tests: Add an awful.placement.next_to test

It was overdue

lib/awful/placement.lua

@@ -1377,6 +1377,8 @@ end
 -- In that case, if there is room on the top of the geometry, then it will have
 -- priority, followed by all the others, in order.
 --
+--@DOC_awful_placement_next_to_EXAMPLE@
+--
 -- @tparam drawable d A wibox or client
 -- @tparam table args
 -- @tparam string args.mode The mode

tests/examples/awful/placement/next_to.lua

@@ -0,0 +1,61 @@
+--DOC_GEN_IMAGE --DOC_HIDE
+local awful = { placement = require("awful.placement") }--DOC_HIDE
+screen[1]._resize {x= 0, width = 640, height=200} --DOC_HIDE
+
+local parent_client = client.gen_fake {x = 0, y = 0, width=350, height=70} --DOC_HIDE
+parent_client:_hide() --DOC_HIDE
+awful.placement.centered(client.focus) --DOC_HIDE
+parent_client:set_label("Parent client") --DOC_HIDE
+
+for _, pos in ipairs{"left", "right", "top", "bottom"} do
+    for _, anchor in ipairs{"front", "middle", "back"} do
+        local c1 = client.gen_fake {x = 0, y = 0, width=80, height=20} --DOC_HIDE
+        c1:_hide() --DOC_HIDE
+        local _,p,a = --DOC_HIDE
+        awful.placement.next_to(
+            client.focus,
+            {
+                preferred_positions = pos,
+                preferred_anchors   = anchor,
+                geometry            = parent_client,
+            }
+        )
+        c1:set_label(pos.."+"..anchor) --DOC_HIDE
+        assert(pos    == p) --DOC_HIDE
+        assert(anchor == a) --DOC_HIDE
+
+        --DOC_HIDE Make sure the border are correctly applied
+        if pos == "left" then  --DOC_HIDE
+            assert(c1.x + c1.width + 2*c1.border_width == parent_client.x) --DOC_HIDE
+        end --DOC_HIDE
+        if pos == "right" then --DOC_HIDE
+            assert(c1.x == parent_client.x+parent_client.width+2*parent_client.border_width) --DOC_HIDE
+        end --DOC_HIDE
+        if pos == "top" then --DOC_HIDE
+            assert(c1.y + c1.height + 2*c1.border_width == parent_client.y) --DOC_HIDE
+        end --DOC_HIDE
+        if pos == "bottom" then --DOC_HIDE
+            assert(c1.y == parent_client.y+parent_client.height+2*parent_client.border_width)--DOC_HIDE
+        end --DOC_HIDE
+
+        --DOC_HIDE Make sure the "children" don't overshoot the parent geometry
+        if pos ~= "right" then --DOC_HIDE
+            assert(c1.x+c1.width+2*c1.border_width--DOC_HIDE
+                <= parent_client.x+parent_client.width+2*parent_client.border_width) --DOC_HIDE
+        end --DOC_HIDE
+        if pos ~= "bottom" then --DOC_HIDE
+            assert(c1.y+c1.height+2*c1.border_width --DOC_HIDE
+                <= parent_client.y+parent_client.height+2*parent_client.border_width) --DOC_HIDE
+        end --DOC_HIDE
+        if pos ~= "left" then --DOC_HIDE
+            assert(c1.x >= parent_client.x) --DOC_HIDE
+        end --DOC_HIDE
+        if pos ~= "top"  then --DOC_HIDE
+            assert(c1.y >= parent_client.y) --DOC_HIDE
+        end --DOC_HIDE
+    end
+end
+
+return {hide_lines=true} --DOC_HIDE
+
+--DOC_HIDE vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80