diff --git a/lib/test.nix b/lib/test.nix
index 151aa1b..4b075ad 100644
--- a/lib/test.nix
+++ b/lib/test.nix
@@ -61,6 +61,11 @@ let
               pname = "poetry-plugin-export";
               version = "1.4.0";
             };
+
+            python3 = {
+              pname = "python3";
+              inherit (pkgs.python3) version;
+            };
           };
           stdenv = {
             inherit isLinux isDarwin;
diff --git a/lib/test_project.nix b/lib/test_project.nix
index 102e38a..276feb9 100644
--- a/lib/test_project.nix
+++ b/lib/test_project.nix
@@ -6,6 +6,10 @@
 }:
 let
   inherit (project) loadPyproject loadPoetryPyproject;
+
+  # Get python packages from a set
+  getPkgs = set: pnames: map (pname: set.pkgs.${pname}) pnames;
+
 in
 {
   loadPyproject = {
@@ -33,90 +37,30 @@ in
           };
           mainProgram = "pdm";
         };
-        nativeBuildInputs = [
-          {
-            pname = "pdm-backend";
-            version = "2.1.4";
-          }
+        nativeBuildInputs = getPkgs mocks.cpythonLinux38 [
+          "pdm-backend"
         ];
         pname = "pdm";
-        propagatedBuildInputs = [
-          {
-            pname = "blinker";
-            version = "1.5";
-          }
-          {
-            pname = "certifi";
-            version = "2023.05.07";
-          }
-          {
-            pname = "packaging";
-            version = "23.1";
-          }
-          {
-            pname = "platformdirs";
-            version = "3.9.1";
-          }
-          {
-            pname = "rich";
-            version = "13.3.5";
-          }
-          {
-            pname = "virtualenv";
-            version = "20.24.0";
-          }
-          {
-            pname = "pyproject-hooks";
-            version = "1.0.0";
-          }
-          {
-            pname = "requests-toolbelt";
-            version = "1.0.0";
-          }
-          {
-            pname = "unearth";
-            version = "0.9.1";
-          }
-          {
-            pname = "findpython";
-            version = "0.4.0";
-          }
-          {
-            pname = "tomlkit";
-            version = "0.12.1";
-          }
-          {
-            pname = "shellingham";
-            version = "1.5.1";
-          }
-          {
-            pname = "python-dotenv";
-            version = "1.0.0";
-          }
-          {
-            pname = "resolvelib";
-            version = "0.5.5";
-          }
-          {
-            pname = "installer";
-            version = "0.7.0";
-          }
-          {
-            pname = "cachecontrol";
-            version = "0.13.1";
-          }
-          {
-            pname = "tomli";
-            version = "2.0.1";
-          }
-          {
-            pname = "importlib-resources";
-            version = "5.12.0";
-          }
-          {
-            pname = "importlib-metadata";
-            version = "6.8.0";
-          }
+        propagatedBuildInputs = getPkgs mocks.cpythonLinux38 [
+          "blinker"
+          "certifi"
+          "packaging"
+          "platformdirs"
+          "rich"
+          "virtualenv"
+          "pyproject-hooks"
+          "requests-toolbelt"
+          "unearth"
+          "findpython"
+          "tomlkit"
+          "shellingham"
+          "python-dotenv"
+          "resolvelib"
+          "installer"
+          "cachecontrol"
+          "tomli"
+          "importlib-resources"
+          "importlib-metadata"
         ];
       };
     };
@@ -133,50 +77,20 @@ in
       expected = {
         format = "pyproject";
         meta = { description = "Powerful data structures for data analysis, time series, and statistics"; };
-        nativeBuildInputs = [
-          {
-            pname = "meson-python";
-            version = "0.13.1";
-          }
-          {
-            pname = "meson";
-            version = "1.2.0";
-          }
-          {
-            pname = "wheel";
-            version = "0.41.1";
-          }
-          {
-            pname = "cython";
-            version = "0.29.36";
-          }
-          {
-            pname = "oldest-supported-numpy";
-            version = "1.0.0";
-          }
-          {
-            pname = "versioneer";
-            version = "0.29";
-          }
+        nativeBuildInputs = getPkgs mocks.cpythonLinux38 [
+          "meson-python"
+          "meson"
+          "wheel"
+          "cython"
+          "oldest-supported-numpy"
+          "versioneer"
         ];
         pname = "pandas";
-        propagatedBuildInputs = [
-          {
-            pname = "numpy";
-            version = "1.25.1";
-          }
-          {
-            pname = "python-dateutil";
-            version = "2.8.2";
-          }
-          {
-            pname = "pytz";
-            version = "2023.3";
-          }
-          {
-            pname = "tzdata";
-            version = "2022.7";
-          }
+        propagatedBuildInputs = getPkgs mocks.cpythonLinux38 [
+          "numpy"
+          "python-dateutil"
+          "pytz"
+          "tzdata"
         ];
       };
     };
@@ -207,130 +121,40 @@ in
             url = "https://spdx.org/licenses/MIT.html";
           };
         };
-        nativeBuildInputs = [
-          {
-            pname = "poetry-core";
-            version = "1.6.1";
-          }
+        nativeBuildInputs = getPkgs mocks.cpythonLinux38 [
+          "poetry-core"
         ];
         pname = "poetry";
-        propagatedBuildInputs = [
-          {
-            pname = "build";
-            version = "0.10.0";
-          }
-          {
-            pname = "cachecontrol";
-            version = "0.13.1";
-          }
-          {
-            pname = "cleo";
-            version = "2.0.1";
-          }
-          {
-            pname = "crashtest";
-            version = "0.4.1";
-          }
-          {
-            pname = "dulwich";
-            version = "0.21.6";
-          }
-          {
-            pname = "filelock";
-            version = "3.12.2";
-          }
-          {
-            pname = "html5lib";
-            version = "1.1";
-          }
-          {
-            pname = "importlib-metadata";
-            version = "6.8.0";
-          }
-          {
-            pname = "installer";
-            version = "0.7.0";
-          }
-          {
-            pname = "jsonschema";
-            version = "4.18.4";
-          }
-          {
-            pname = "keyring";
-            version = "24.2.0";
-          }
-          {
-            pname = "lockfile";
-            version = "0.12.2";
-          }
-          {
-            pname = "packaging";
-            version = "23.1";
-          }
-          {
-            pname = "pexpect";
-            version = "4.8.0";
-          }
-          {
-            pname = "pkginfo";
-            version = "1.9.6";
-          }
-          {
-            pname = "platformdirs";
-            version = "3.9.1";
-          }
-          {
-            pname = "poetry-core";
-            version = "1.6.1";
-          }
-          {
-            pname = "poetry-plugin-export";
-            version = "1.4.0";
-          }
-          {
-            pname = "pyproject-hooks";
-            version = "1.0.0";
-          }
-          {
-            pname = "python3";
-            version = "3.10.12";
-          }
-          {
-            pname = "requests";
-            version = "2.31.0";
-          }
-          {
-            pname = "requests-toolbelt";
-            version = "1.0.0";
-          }
-          {
-            pname = "shellingham";
-            version = "1.5.1";
-          }
-          {
-            pname = "tomli";
-            version = "2.0.1";
-          }
-          {
-            pname = "tomlkit";
-            version = "0.12.1";
-          }
-          {
-            pname = "trove-classifiers";
-            version = "2023.7.6";
-          }
-          {
-            pname = "urllib3";
-            version = "1.26.16";
-          }
-          {
-            pname = "virtualenv";
-            version = "20.24.0";
-          }
-          {
-            pname = "pre-commit";
-            version = "3.3.3";
-          }
+        propagatedBuildInputs = getPkgs mocks.cpythonLinux38 [
+          "build"
+          "cachecontrol"
+          "cleo"
+          "crashtest"
+          "dulwich"
+          "filelock"
+          "html5lib"
+          "importlib-metadata"
+          "installer"
+          "jsonschema"
+          "keyring"
+          "lockfile"
+          "packaging"
+          "pexpect"
+          "pkginfo"
+          "platformdirs"
+          "poetry-core"
+          "poetry-plugin-export"
+          "pyproject-hooks"
+          "python3"
+          "requests"
+          "requests-toolbelt"
+          "shellingham"
+          "tomli"
+          "tomlkit"
+          "trove-classifiers"
+          "urllib3"
+          "virtualenv"
+          "pre-commit"
         ];
         version = "1.4.2";
       };