Simplify the location expansion integration test

It now only tests the correct mapping of paths in the local workspace
and in an external workspace. The parsing of more complicated location
strings is tested in the unit tests.

Addressing review comment
#132 (comment)

WORKSPACE

@@ -174,25 +174,26 @@ nixpkgs_package(
     repository = "@remote_nixpkgs",
 )
 
+local_repository(
+    name = "nixpkgs_location_expansion_test_file",
+    path = "tests/location_expansion/test_repo",
+)
+
 nixpkgs_package(
     name = "nixpkgs_location_expansion_test",
     build_file_content = "exports_files(glob(['out/**']))",
     nix_file = "//tests:location_expansion.nix",
     nix_file_deps = [
-        "//:nixpkgs.json",
-        "//:nixpkgs.nix",
-        "@io_tweag_rules_nixpkgs//tests:relative_imports/nixpkgs.nix",
+        "//tests:location_expansion/test_file",
+        "@nixpkgs_location_expansion_test_file//:test_file",
     ],
     nixopts = [
         "--arg",
-        "attrs",
-        "{ nixpkgs_json = $(location //:nixpkgs.json); nixpkgs_nix = $(location //:nixpkgs.nix); }",
+        "local_file",
+        "$(location //tests:location_expansion/test_file)",
         "--arg",
-        "relative_imports",
-        "$(location @io_tweag_rules_nixpkgs//tests:relative_imports/nixpkgs.nix)",
-        "--argstr",
-        "escaped_string",
-        "$$ $$(location //:does-not-exist) )(",
+        "external_file",
+        "$(location @nixpkgs_location_expansion_test_file//:test_file)",
     ],
     repository = "@remote_nixpkgs",
 )

tests/BUILD.bazel

@@ -63,24 +63,14 @@ sh_test(
     srcs = ["location_expansion.sh"],
     args = [
         "$(POSIX_DIFF)",
-        "$(rootpath //:nixpkgs.json)",
-        "$(rootpath //:nixpkgs.nix)",
-        "$(rootpath //tests:relative_imports/nixpkgs.nix)",
-        "$(rootpath //tests:location_expansion/escaped_string)",
-        "$(rootpath @nixpkgs_location_expansion_test//:out/nixpkgs.json)",
-        "$(rootpath @nixpkgs_location_expansion_test//:out/nixpkgs.nix)",
-        "$(rootpath @nixpkgs_location_expansion_test//:out/relative_imports.nix)",
-        "$(rootpath @nixpkgs_location_expansion_test//:out/escaped_string)",
+        "$(rootpath //tests:location_expansion/test_file)",
+        "$(rootpath @nixpkgs_location_expansion_test//:out/local_file)",
+        "$(rootpath @nixpkgs_location_expansion_test//:out/external_file)",
     ],
     data = [
-        "//:nixpkgs.json",
-        "//:nixpkgs.nix",
-        "//tests:location_expansion/escaped_string",
-        "//tests:relative_imports/nixpkgs.nix",
-        "@nixpkgs_location_expansion_test//:out/escaped_string",
-        "@nixpkgs_location_expansion_test//:out/nixpkgs.json",
-        "@nixpkgs_location_expansion_test//:out/nixpkgs.nix",
-        "@nixpkgs_location_expansion_test//:out/relative_imports.nix",
+        "//tests:location_expansion/test_file",
+        "@nixpkgs_location_expansion_test//:out/external_file",
+        "@nixpkgs_location_expansion_test//:out/local_file",
     ],
     toolchains = ["@rules_sh//sh/posix:make_variables"],
 )

tests/location_expansion.nix

@@ -1,6 +1,6 @@
 with import <nixpkgs> { config = {}; overlays = []; };
 
-{ attrs, relative_imports, escaped_string }:
+{ local_file, external_file }:
 let
   inherit (attrs) nixpkgs_json nixpkgs_nix;
 in
@@ -11,8 +11,6 @@ in
     }
     ''
       mkdir -p $out/out
-      cp ${nixpkgs_json} $out/out/nixpkgs.json
-      cp ${nixpkgs_nix} $out/out/nixpkgs.nix
-      cp ${relative_imports} $out/out/relative_imports.nix
-      echo '${escaped_string}' >$out/out/escaped_string
+      cp ${local_file} $out/out/local_file
+      cp ${external_file} $out/out/external_file
     ''

tests/location_expansion.sh

@@ -1,6 +1,13 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# USAGE:
+# location_expansion.sh DIFF REFERENCE FILE...
+#
+# Compares the given files to the reference file and fails if there is a difference.
 DIFF="$1"
+REFERENCE="$2"
 
-diff "$2" "$6"
-diff "$3" "$7"
-diff "$4" "$8"
-diff "$5" "$9"
+for file in "${@:3}"; do
+  "$DIFF" "$file" "$REFERENCE"
+done

tests/location_expansion/test_file

@@ -0,0 +1,11 @@
+# A few random numbers
+3030205
+68380721
+93196393
+70110283
+92132420
+98602836
+37655207
+12502743
+73421895
+75878115

tests/location_expansion/test_repo/BUILD.bazel

@@ -0,0 +1 @@
+exports_files(glob(["*"]))

tests/location_expansion/test_repo/test_file

@@ -0,0 +1 @@
+../test_file