Add file-based script execution in ScriptRunner

Author: gaggle

lib/script_runner.ex

@@ -25,15 +25,27 @@ defmodule ElixirScript.ScriptRunner do
 
     Logger.debug("Created GitHub client: #{inspect(client)}")
 
+    bindings = [
+      context: Context.from_github_environment(),
+      client: client
+    ]
+
     {value, _binding} =
-      Code.eval_string(
-        script,
-        context: Context.from_github_environment(),
-        client: client
-      )
+      if is_file_path?(script) do
+        path = Path.expand(script)
+        content = File.read!(path)
+        Code.eval_string(content, bindings, file: path, line: 1)
+      else
+        Code.eval_string(script, bindings)
+      end
 
     value
   end
 
+  # Determines if the given string is a file path
+  defp is_file_path?(script) when is_binary(script) do
+    String.starts_with?(script, ["./", "../", "/"])
+  end
+
   defp tentacat_client, do: Application.get_env(:script_runner, :tentacat_client, Tentacat.Client)
 end

test/script_runner_test.exs

@@ -6,6 +6,15 @@ defmodule ElixirScript.ScriptRunnerTest do
   alias ElixirScript.ScriptRunner
   alias Test.Fixtures.GitHubWorkflowRun
 
+  # Create a temporary file with automatic cleanup
+  # Returns the full path to the created file
+  defp create_temp_file(filename, content) do
+    path = Path.join(System.tmp_dir(), filename)
+    File.write!(path, content)
+    on_exit(fn -> File.rm!(path) end)
+    path
+  end
+
   setup do
     stub(SystemEnvMock, :get_env, fn varname, default ->
       GitHubWorkflowRun.env()[varname] || default
@@ -34,6 +43,116 @@ defmodule ElixirScript.ScriptRunnerTest do
     end
   end
 
+  describe "file-based scripts" do
+    test "can execute scripts from file paths" do
+      file_path = create_temp_file("test_script.exs", "\"Hello from test file\"")
+      assert ScriptRunner.run(file_path) == "Hello from test file"
+    end
+
+    test "file scripts have access to context bindings" do
+      file_path = create_temp_file("context_test.exs", ~S["Actor is: #{context.actor}"])
+      assert ScriptRunner.run(file_path) == "Actor is: gaggle"
+    end
+
+    test "file scripts have access to client bindings" do
+      file_path = create_temp_file("client_test.exs", "inspect(client)")
+      result = ScriptRunner.run(file_path)
+      assert result =~ "auth: nil"
+    end
+
+    test "auto-detects file paths vs inline scripts" do
+      # Test detection by behavior - file paths cause File.Error
+      assert_raise File.Error, fn ->
+        ScriptRunner.run("./non_existent.exs")
+      end
+
+      assert_raise File.Error, fn ->
+        ScriptRunner.run("../non_existent.exs")
+      end
+
+      assert_raise File.Error, fn ->
+        ScriptRunner.run("/non_existent.exs")
+      end
+
+      # Inline scripts should be evaluated as code
+      assert ScriptRunner.run("1 + 1") == 2
+      assert ScriptRunner.run("\"hello\"") == "hello"
+    end
+
+    test "raises clear error when file doesn't exist" do
+      assert_raise File.Error, ~r/no such file or directory/, fn ->
+        ScriptRunner.run("./non_existent_file.exs")
+      end
+    end
+
+    test "handles empty file gracefully" do
+      file_path = create_temp_file("empty.exs", "")
+      # Elixir naturally returns nil for empty files
+      assert ScriptRunner.run(file_path) == nil
+    end
+
+    test "handles files returning nil" do
+      file_path = create_temp_file("nil_return.exs", "IO.puts(\"side effect\")\nnil")
+      assert ScriptRunner.run(file_path) == nil
+    end
+
+    test "works with any file extension containing valid Elixir code" do
+      # .ex files work
+      ex_file = create_temp_file("test.ex", "\"from .ex\"")
+      assert ScriptRunner.run(ex_file) == "from .ex"
+
+      # .txt files work if they contain Elixir
+      txt_file = create_temp_file("test.txt", "\"from .txt\"")
+      assert ScriptRunner.run(txt_file) == "from .txt"
+
+      # No extension works too
+      no_ext = create_temp_file("testfile", "\"no extension\"")
+      assert ScriptRunner.run(no_ext) == "no extension"
+    end
+
+    test "gives helpful error for non-Elixir content" do
+      file_path = create_temp_file("not_elixir.txt", "This is just plain text, not Elixir code")
+      # Should get a syntax error with the filename in the message
+      exception =
+        assert_raise SyntaxError, fn ->
+          ScriptRunner.run(file_path)
+        end
+
+      # The error includes the file path, helping users identify the problem
+      assert exception.file =~ "not_elixir.txt"
+    end
+
+    test "preserves proper file semantics like __DIR__ and __ENV__" do
+      file_path = create_temp_file("file_semantics.exs", "{__DIR__, __ENV__.file}")
+      {dir, file} = ScriptRunner.run(file_path)
+
+      # __DIR__ should be the directory containing the file
+      assert dir == Path.dirname(Path.expand(file_path))
+
+      # __ENV__.file should be the absolute path to the file
+      assert file == Path.expand(file_path)
+    end
+
+    test "supports relative requires within files" do
+      dir = Path.join(System.tmp_dir(), "require_test_#{:rand.uniform(1000)}")
+      File.mkdir!(dir)
+
+      helper_path = Path.join(dir, "my_helper.exs")
+      File.write!(helper_path, "defmodule MyHelper do\n  def value, do: :from_helper\nend")
+
+      main_path = Path.join(dir, "main.exs")
+      File.write!(main_path, "Code.require_file(\"./my_helper.exs\", __DIR__)\nMyHelper.value()")
+
+      on_exit(fn ->
+        File.rm!(main_path)
+        File.rm!(helper_path)
+        File.rmdir!(dir)
+      end)
+
+      assert ScriptRunner.run(main_path) == :from_helper
+    end
+  end
+
   describe "github access" do
     test "executes with an un-authenticated Tentacat GitHub client by default" do
       expect(TentacatMock.ClientMock, :new, fn -> %{auth: nil, endpoint: "github"} end)