feat(async): allow for a.promisify to reject (#557)

2 files changed, 26 insertions, 2 deletions

diff --git a/lua/nvim-lsp-installer/core/async/init.lua b/lua/nvim-lsp-installer/core/async/init.lua
index 85f4c83c..6ecb5a61 100644
--- a/lua/nvim-lsp-installer/core/async/init.lua
+++ b/lua/nvim-lsp-installer/core/async/init.lua
@@ -37,11 +37,23 @@ local function table_pack(...)
     return { n = select("#", ...), ... }
 end
 
-local function promisify(async_fn)
+---@param async_fn fun(...)
+---@param should_reject_err boolean|nil @Whether the provided async_fn takes a callback with the signature `fun(err, result)`
+local function promisify(async_fn, should_reject_err)
     return function(...)
         local args = table_pack(...)
         return await(function(resolve, reject)
-            args[args.n + 1] = resolve
+            if should_reject_err then
+                args[args.n + 1] = function(err, result)
+                    if err then
+                        reject(err)
+                    else
+                        resolve(result)
+                    end
+                end
+            else
+                args[args.n + 1] = resolve
+            end
             local ok, err = pcall(async_fn, unpack(args, 1, args.n + 1))
             if not ok then
                 reject(err)
diff --git a/tests/core/async/async_spec.lua b/tests/core/async/async_spec.lua
index 88af14af..662e493a 100644
--- a/tests/core/async/async_spec.lua
+++ b/tests/core/async/async_spec.lua
@@ -36,6 +36,18 @@ describe("async", function()
     )
 
     it(
+        "should reject callback-style functions",
+        async_test(function()
+            local err = assert.has_error(function()
+                a.promisify(function(arg1, cb)
+                    cb(arg1, nil)
+                end, true) "påskmust"
+            end)
+            assert.equals(err, "påskmust")
+        end)
+    )
+
+    it(
         "should return all values",
         async_test(function()
             local val1, val2, val3 = a.wait(function(resolve)