Add a manual test suite

README.md

@@ -159,3 +159,9 @@ nix-build -E "with import ./default.nix {}; nixGLCommon nixGLIntel"
 `nixGL` is badly tested, mostly because it is difficult to test automatically in a continuous integration context because you need access to different type of hardware.
 
 Some OpenGL configurations may not work, for example AMD proprietary drivers. There is no fundamental limitation, so if you want support for theses configurations, open an issue.
+
+# Hacking
+
+One great way to contribute to nixGL is to run the test suite. Just run
+`./Test.hs` in the main directory and check that all the test relevant to your
+hardware are green.

Test.hs

@@ -0,0 +1,50 @@
+#!/usr/bin/env nix-shell
+#!nix-shell -i runhaskell -p "haskellPackages.ghcWithPackages(p: with p; [hspec process])" -p nix
+{-# LANGUAGE OverloadedStrings #-}
+import Test.Hspec
+import System.Process
+import qualified Data.Text as Text
+import Data.Text (Text)
+import Control.Monad.IO.Class (liftIO)
+import Data.List (find)
+
+-- | Utils function: run a command and returns its output.
+processOutput p args = Text.strip . Text.pack <$> readProcess (Text.unpack p) (Text.unpack <$> args) ""
+
+-- | Returns the path to the nixGLXXX binary.
+nixGLBin version = (<>("/bin/"<>version)) <$> processOutput "nix-build" ["./", "-A", version]
+
+-- | Returns the vendor string associated with a glxinfo wrapped by a nixGL.
+getVendorString nixGL glxinfo = do
+  output <- Text.lines <$> processOutput nixGL [glxinfo]
+  pure $ Text.unpack <$> find ("OpenGL version string"`Text.isPrefixOf`) output
+
+-- | Checks that a nixGL wrapper works with glxinfo 32 & 64 bits.
+checkOpenGL_32_64 glxinfo32 glxinfo64 vendorName nixGLName = do
+  nixGLBin <- runIO $ (<>("/bin/"<>nixGLName)) <$> processOutput "nix-build" ["./", "-A", nixGLName]
+
+  it "32 bits" $ do
+    Just vendorString <- getVendorString nixGLBin glxinfo32
+    vendorString `shouldContain` vendorName
+
+  it "64 bits" $ do
+    Just vendorString <- getVendorString nixGLBin glxinfo64
+    vendorString `shouldContain` vendorName
+
+main = do
+  glxinfo64 <- (<>"/bin/glxinfo") <$> processOutput "nix-build" ["<nixpkgs>", "-A", "glxinfo"]
+  glxinfo32 <- (<>"/bin/glxinfo") <$> processOutput "nix-build" ["<nixpkgs>", "-A", "pkgsi686Linux.glxinfo"]
+
+  let checkOpenGL = checkOpenGL_32_64 glxinfo32 glxinfo64
+
+  hspec $ do
+    describe "Mesa" $ do
+      checkOpenGL "Mesa" "nixGLIntel"
+    describe "Nvidia - Bumblebee" $ do
+      checkOpenGL "NVIDIA" "nixGLNvidiaBumblebee"
+
+    -- TODO: check Nvidia (I don't have this hardware)
+    describe "Nvidia" $ do
+      checkOpenGL "NVIDIA" "nixGLNvidia"
+
+    -- TODO: check vulkan (I don't have vulkan compatible hardware)