Merge pull request #3071 from actionless/fix-empty-string-matcher

fix(gears: matcher: default_matcher): handle sidecase of string.match-ing the empty string ('')

lib/gears/matcher.lua

@@ -79,7 +79,13 @@ local matcher = {}
 -- @see remove_matching_source
 
 local function default_matcher(a, b)
-    return a == b or (type(a) == "string" and a:match(b))
+    local result = a == b
+    if result then return true end
+    if type(a) == "string" and type(b) == "string" then
+      result = a:match(b)
+      if result == '' then return false end
+    end
+    return result
 end
 
 local function greater_matcher(a, b)

spec/gears/matcher_spec.lua

@@ -0,0 +1,46 @@
+---------------------------------------------------------------------------
+-- @author Yauheni Kirylau
+-- @copyright 2020 Yauheni Kirylau
+---------------------------------------------------------------------------
+
+local matcher = require("gears.matcher")
+
+local matcher_instance = matcher()
+local test_obj = {
+    foo='bar',
+    spam='',
+}
+
+describe("gears.matcher", function()
+
+    describe("matching by normal string value", function()
+        local rule = {
+            foo='bar',
+        }
+        assert.is_true(matcher_instance:_match(test_obj, rule))
+    end)
+
+    describe("not matching by normal string value", function()
+        local rule = {
+            foo='nah',
+        }
+        assert.is_false(matcher_instance:_match(test_obj, rule))
+    end)
+
+    describe("matching by empty string value", function()
+        local rule = {
+            spam='',
+        }
+        assert.is_true(matcher_instance:_match(test_obj, rule))
+    end)
+
+    describe("not matching by empty string value", function()
+        local rule = {
+            foo='',
+        }
+        assert.is_false(matcher_instance:_match(test_obj, rule))
+    end)
+
+end)
+
+-- vim: filetype=lua:expandtab:shiftwidth=4:tabstop=8:softtabstop=4:textwidth=80