output missing/substitutable derivations in eval output

tests/assets/ci.nix

@@ -0,0 +1,5 @@
+with import <nixpkgs> {};
+{
+  builtJob = pkgs.writeText "job1" "job1";
+  substitutedJob = pkgs.hello;
+}

tests/assets/flake.lock

@@ -0,0 +1,26 @@
+{
+  "nodes": {
+    "nixpkgs": {
+      "locked": {
+        "lastModified": 1616345250,
+        "narHash": "sha256-WLbLFIJyKCklGyEMGwh9XDTzafafyO95s4+rJHOc/Ag=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "5e4a4e0c32f0ca0a5bd4ebbbf17aedd347de7f3e",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
+    "root": {
+      "inputs": {
+        "nixpkgs": "nixpkgs"
+      }
+    }
+  },
+  "root": "root",
+  "version": 7
+}

tests/assets/flake.nix

@@ -0,0 +1,12 @@
+{
+  inputs.nixpkgs.url = "github:NixOS/nixpkgs";
+
+  outputs = { self, nixpkgs }: let
+    pkgs = nixpkgs.legacyPackages.x86_64-linux;
+  in {
+    hydraJobs = {
+      builtJob = pkgs.writeText "job1" "job1";
+      substitutedJob = pkgs.hello;
+    };
+  };
+}

tests/test_eval.py

@@ -0,0 +1,34 @@
+#!/usr/bin/env python3
+
+import subprocess
+import json
+from tempfile import TemporaryDirectory
+from pathlib import Path
+from typing import List
+
+TEST_ROOT = Path(__file__).parent.resolve()
+PROJECT_ROOT = TEST_ROOT.parent
+BIN = PROJECT_ROOT.joinpath("build", "src", "hydra-eval-jobs")
+
+
+def common_test(extra_args: List[str]) -> None:
+    with TemporaryDirectory() as tempdir:
+        cmd = [str(BIN), "--gc-roots-dir", tempdir] + extra_args
+        res = subprocess.run(
+            cmd,
+            cwd=TEST_ROOT.joinpath("assets"),
+            text=True,
+            check=True,
+            stdout=subprocess.PIPE,
+        )
+        data = json.loads(res.stdout)
+        assert len(data["builtJob"]["builds"]) == 1
+        assert len(data["substitutedJob"]["substitutes"]) >= 1
+
+
+def test_flake() -> None:
+    common_test(["--flake", ".#"])
+
+
+def test_expression() -> None:
+    common_test(["ci.nix"])