fix(spawn): fix Failure.tostring when unable to retrieve uv_handle

2 files changed, 36 insertions, 1 deletions

diff --git a/lua/nvim-lsp-installer/core/spawn.lua b/lua/nvim-lsp-installer/core/spawn.lua
index 4776ff66..8ac06aa4 100644
--- a/lua/nvim-lsp-installer/core/spawn.lua
+++ b/lua/nvim-lsp-installer/core/spawn.lua
@@ -24,7 +24,11 @@ local spawn = {
 local function Failure(err, cmd)
     return Result.failure(setmetatable(err, {
         __tostring = function()
-            return ("spawn: %s failed with exit code %d"):format(cmd, err.exit_code)
+            if err.exit_code ~= nil then
+                return ("spawn: %s failed with exit code %d. %s"):format(cmd, err.exit_code, err.stderr or "")
+            else
+                return ("spawn: %s failed with no exit code. %s"):format(cmd, err.stderr or "")
+            end
         end,
     }))
 end
diff --git a/tests/core/spawn_spec.lua b/tests/core/spawn_spec.lua
index 176135ee..7c0a27f8 100644
--- a/tests/core/spawn_spec.lua
+++ b/tests/core/spawn_spec.lua
@@ -1,4 +1,5 @@
 local spy = require "luassert.spy"
+local stub = require "luassert.stub"
 local match = require "luassert.match"
 local spawn = require "nvim-lsp-installer.core.spawn"
 local process = require "nvim-lsp-installer.process"
@@ -113,4 +114,34 @@ describe("async spawn", function()
             assert.is_true(result:is_failure())
         end)
     )
+
+    it(
+        "should handle failure to spawn process",
+        async_test(function()
+            stub(process, "spawn", function(_, _, callback)
+                callback(false)
+            end)
+
+            local result = spawn.my_cmd {}
+            assert.is_true(result:is_failure())
+            assert.is_nil(result:err_or_nil().exit_code)
+        end)
+    )
+
+    it(
+        "should format failure message",
+        async_test(function()
+            stub(process, "spawn", function(cmd, opts, callback)
+                opts.stdio_sink.stderr(("This is an error message for %s!"):format(cmd))
+                callback(false, 127)
+            end)
+
+            local result = spawn.my_cmd {}
+            assert.is_true(result:is_failure())
+            assert.equals(
+                "spawn: my_cmd failed with exit code 127. This is an error message for my_cmd!",
+                tostring(result:err_or_nil())
+            )
+        end)
+    )
 end)