Add ale.has to mirror ale#Has in Lua

doc/ale.txt

@@ -4486,9 +4486,12 @@ ale#GetFilenameMappings(buffer, name)               *ale#GetFilenameMappings()*
   See |g:ale_filename_mappings| for details on filename mapping.
 
 
+ale.has(feature)                                                    *ale.has()*
 ale#Has(feature)                                                    *ale#Has()*
 
-  Return `1` if ALE supports a given feature, like |has()| for Vim features.
+  In Vim, `ale#Has` returns `1` if ALE supports a given feature, like |has()|
+  for Vim features. In Lua `ale.has` returns `true` instead, and `false` if a
+  feature is not supported.
 
   ALE versions can be checked with version strings in the format
   `ale#Has('ale-x.y.z')`, such as `ale#Has('ale-2.4.0')`.

lua/ale/init.lua

@@ -55,6 +55,15 @@ ale.setup = setmetatable({
     end,
 })
 
+---Check if ALE supports a given feature.
+---
+---The ALE version can be checked with ale.has("ale-1.0.0"), etc.
+---@param feature string The feature to test for.
+---@return boolean supported If the feature is supported.
+ale.has = function(feature)
+    return vim.fn["ale#Has"](feature) == 1
+end
+
 ---Get an ALE variable for a buffer (first) or globally (second)
 ---@param buffer number The buffer number to retreive the variable for.
 ---@param variable_name string The variable to retrieve.

test/lua/ale_has_spec.lua

@@ -0,0 +1,27 @@
+local eq = assert.are.same
+local ale = require("ale")
+
+describe("ale.has", function()
+    setup(function()
+        _G.vim = {
+            fn = {
+                ["ale#Has"] = function(feature)
+                    if feature == "ale-4.0.0" then
+                        return 1
+                    end
+
+                    return 0
+                end,
+            },
+        }
+    end)
+
+    teardown(function()
+        _G.vim = nil
+    end)
+
+    it("should return valuse from ale#Has correctly", function()
+        eq(true, ale.has("ale-4.0.0"))
+        eq(false, ale.has("ale-20.0.0"))
+    end)
+end)