flake reorg, nix integration testing

nix/test-runner.nix

@@ -0,0 +1,42 @@
+{
+  rustPlatform,
+  openssl,
+  pkg-config,
+  lib,
+}: let
+  inherit (lib.sources) sourceByRegex;
+  inherit (builtins) fromTOML readFile;
+  src = sourceByRegex ../. ["Cargo.*" "(src|tests)(/.*)?"];
+  cargoPackage = (fromTOML (readFile ../Cargo.toml)).package;
+in
+  rustPlatform.buildRustPackage {
+    pname = cargoPackage.name;
+    inherit (cargoPackage) version;
+
+    inherit src;
+
+    buildInputs = [
+      openssl
+    ];
+
+    nativeBuildInputs = [
+      pkg-config
+    ];
+
+    doCheck = false;
+
+    buildPhase = ''
+      cargo build --tests
+    '';
+
+    installPhase = ''
+      mkdir -p $out/bin
+      cp target/debug/deps/tests-???????????????? $out/bin/api-test
+    '';
+
+    cargoLock = {
+      lockFile = ../Cargo.lock;
+    };
+
+    meta.mainProgram = "api-test";
+  }