fix: properly link playwright executables

Previously were hardcoding paths and versions that we could just link directly
to the test runner, which we are now doing!

Author: Camsbury

shell.nix

@@ -2,45 +2,32 @@ let
   pkgs = import ./nix/pinned.nix {
     overlays = [(import ./nix/overlays.nix)];
   };
+  inherit (pkgs.stdenv.hostPlatform) system;
+  throwSystem = throw "Unsupported system: ${system}";
+  suffix =
+    {
+      x86_64-linux = "linux64";
+      aarch64-linux = "linux-arm64";
+      x86_64-darwin = "mac64";
+      aarch64-darwin = "mac-arm64";
+    }.${system} or throwSystem;
 in
 with pkgs;
 mkShell {
+  nativeBuildInputs = [
+    playwright-driver.browsers
+  ];
   buildInputs = [
     babashka
     clojure
     cljfmt
     clj-kondo
     neil
-
-    # Needed for Playwright (wally) e2e tests on NixOS.
-    # Playwright Java ships its own node binary, which is dynamically linked
-    # and won't run on NixOS by default; we point Playwright at Nix's node and
-    # use Nix's Chromium binary.
-    nodejs
-    chromium
   ];
-
-  shellHook = ''
-    # Playwright Java (via wally) runs on NixOS when we:
-    # - prevent Playwright from downloading its own browsers (they're not Nix-patched)
-    # - provide a "fake" Playwright browser installation that delegates to Nix's Chromium
-    # - ensure a working Node is available
-
-    export PLAYWRIGHT_NODEJS_PATH="${nodejs}/bin/node"
-    export PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD=1
-
-    # Playwright 1.31.0 expects Chromium revision 1048 at this path.
-    export PLAYWRIGHT_BROWSERS_PATH="$HOME/.cache/ms-playwright"
-    chromium_dir="$PLAYWRIGHT_BROWSERS_PATH/chromium-1048/chrome-linux"
-    mkdir -p "$chromium_dir"
-
-    chromium_wrapper="$chromium_dir/chrome"
-    if [ ! -e "$chromium_wrapper" ]; then
-      cat > "$chromium_wrapper" <<'EOF'
-#!/usr/bin/env bash
-exec "${chromium}/bin/chromium" "$@"
-EOF
-      chmod +x "$chromium_wrapper"
-    fi
-  '';
+  PLAYWRIGHT_BROWSERS_PATH = "${pkgs.playwright-driver.browsers}";
+  PLAYWRIGHT_CHROMIUM_EXECUTABLE_PATH = "${pkgs.playwright-driver.browsers}/chromium_headless_shell-${pkgs.playwright-driver.browsersJSON.chromium-headless-shell.revision}/chrome-headless-shell-${suffix}/chrome-headless-shell";
+  PLAYWRIGHT_SKIP_VALIDATE_HOST_REQUIREMENTS = true;
+  PLAYWRIGHT_SKIP_BROWSER_DOWNLOAD = 1;
+  PLAYWRIGHT_HOST_PLATFORM_OVERRIDE = "ubuntu-24.04";
+  PLAYWRIGHT_NODEJS_PATH="${pkgs.nodejs}/bin/node";
 }

test/hyper/e2e_test.clj

@@ -5,7 +5,8 @@
    titles, and Var-based live reload of inline route handlers.
 
    Run with: clojure -M:test --focus :e2e"
-  (:require [clojure.test :refer [deftest is testing use-fixtures]]
+  (:require [clojure.string :as str]
+            [clojure.test :refer [deftest is testing use-fixtures]]
             [hyper.core :as h]
             [hyper.state :as state]
             [wally.main :as w])
@@ -129,11 +130,20 @@
 ;; ---------------------------------------------------------------------------
 
 (defn launch-browser
-  "Launch a headless Chromium browser. Returns {:playwright pw :browser browser}."
+  "Launch a headless Chromium browser. Returns {:playwright pw :browser browser}.
+
+   If PLAYWRIGHT_CHROMIUM_EXECUTABLE_PATH is set, we launch that Chromium
+   binary instead of Playwright's downloaded browser bundle."
   []
-  (let [pw      (Playwright/create)
-        browser (.. pw chromium (launch (doto (BrowserType$LaunchOptions.)
-                                          (.setHeadless true))))]
+  (let [pw              (Playwright/create)
+        executable-path (some-> (System/getenv "PLAYWRIGHT_CHROMIUM_EXECUTABLE_PATH")
+                                (str/trim)
+                                (not-empty))
+        opts            (doto (BrowserType$LaunchOptions.)
+                          (.setHeadless true))
+        _               (when executable-path
+                          (.setExecutablePath opts (java.nio.file.Path/of executable-path (into-array String []))))
+        browser         (.. pw chromium (launch opts))]
     {:playwright pw :browser browser}))
 
 (defn new-context