fix(async): pcall callback-style functions to catch errors (#515)

2 files changed, 32 insertions, 9 deletions

diff --git a/lua/nvim-lsp-installer/core/async/init.lua b/lua/nvim-lsp-installer/core/async/init.lua
index a9c1704c..1dd2c138 100644
--- a/lua/nvim-lsp-installer/core/async/init.lua
+++ b/lua/nvim-lsp-installer/core/async/init.lua
@@ -6,15 +6,23 @@ local Promise = {}
 Promise.__index = Promise
 
 function Promise.new(resolver)
-    return setmetatable({ resolver = resolver }, Promise)
+    return setmetatable({ resolver = resolver, has_resolved = false }, Promise)
+end
+
+---@param success boolean
+---@param cb fun()
+function Promise:_wrap_resolver_cb(success, cb)
+    return function(...)
+        if self.has_resolved then
+            return
+        end
+        self.has_resolved = true
+        cb(success, ...)
+    end
 end
 
 function Promise:__call(callback)
-    self.resolver(function(...)
-        callback(true, ...)
-    end, function(...)
-        callback(false, ...)
-    end)
+    self.resolver(self:_wrap_resolver_cb(true, callback), self:_wrap_resolver_cb(false, callback))
 end
 
 local function await(resolver)
@@ -28,9 +36,12 @@ end
 local function promisify(async_fn)
     return function(...)
         local args = table_pack(...)
-        return await(function(resolve)
+        return await(function(resolve, reject)
             args[args.n + 1] = resolve
-            async_fn(unpack(args, 1, args.n + 1))
+            local ok, err = pcall(async_fn, unpack(args, 1, args.n + 1))
+            if not ok then
+                reject(err)
+            end
         end)
     end
 end
diff --git a/tests/core/async_spec.lua b/tests/core/async_spec.lua
index 42c1fe65..7d965e9b 100644
--- a/tests/core/async_spec.lua
+++ b/tests/core/async_spec.lua
@@ -1,5 +1,6 @@
 local assert = require "luassert"
 local spy = require "luassert.spy"
+local match = require "luassert.match"
 local a = require "nvim-lsp-installer.core.async"
 local process = require "nvim-lsp-installer.process"
 
@@ -15,7 +16,7 @@ describe("async", function()
             a.sleep(1000)
         end)
         local stop = timestamp()
-        local grace_ms = 5
+        local grace_ms = 25
         assert.is_true((stop - start) >= (1000 - grace_ms))
     end)
 
@@ -47,4 +48,15 @@ describe("async", function()
             assert.spy(james_bond).was_not.called()
         end)
     )
+
+    it(
+        "should reject if async function raises error",
+        async_test(function()
+            local ok, err = a.promisify(function()
+                error "something went wrong"
+            end)()
+            assert.is_false(ok)
+            assert.is_true(match.has_match "something went wrong$"(err))
+        end)
+    )
 end)