tests/functional2: provide a way to easily access often used assets

Change-Id: I461ee08d9752d972e7485e15186426f98e68ba13

tests/functional2/testlib/global_assets/config.nix.template

@@ -0,0 +1,28 @@
+let
+  contentAddressedByDefault = builtins.getEnv "NIX_TESTS_CA_BY_DEFAULT" == "1";
+  caArgs = if contentAddressedByDefault then {
+    __contentAddressed = true;
+    outputHashMode = "recursive";
+    outputHashAlgo = "sha256";
+  } else {};
+in
+
+rec {
+  path = "@path@";
+
+  system = "@system@";
+
+  shared = builtins.getEnv "_NIX_TEST_SHARED";
+
+  mkDerivation = args:
+    derivation ({
+      inherit system;
+      builder = "/bin/sh";
+      args = ["-e" args.builder or (builtins.toFile "builder-${args.name}.sh" ''
+        if [ -e "$NIX_ATTRS_SH_FILE" ]; then source $NIX_ATTRS_SH_FILE; fi;
+        eval "$buildCommand"
+      '')];
+      PATH = path;
+    } // caArgs // removeAttrs args ["builder" "meta"])
+    // { meta = args.meta or {}; };
+}

tests/functional2/testlib/global_assets/dependencies.builder0.sh

@@ -0,0 +1,17 @@
+[ "${input1: -2}" = /. ]
+[ "${input2: -2}" = /. ]
+
+echo $PATH
+mkdir $out
+echo $(cat $input1/foo)$(cat $input2/bar) > $out/foobar
+
+ln -s $input2 $out/reference-to-input-2
+
+# Self-reference.
+ln -s $out $out/self
+
+# Executable.
+echo program > $out/program
+chmod +x $out/program
+
+echo FOO

tests/functional2/testlib/global_assets/dependencies.nix

@@ -0,0 +1,48 @@
+{ hashInvalidator ? "" }:
+with import ./config.nix;
+
+let
+  input0 = mkDerivation {
+    name = "dependencies-input-0";
+    buildCommand = "mkdir $out; echo foo > $out/bar";
+  };
+
+  input1 = mkDerivation {
+    name = "dependencies-input-1";
+    buildCommand = "mkdir $out; echo FOO > $out/foo";
+  };
+
+  input2 = mkDerivation {
+    name = "dependencies-input-2";
+    buildCommand = ''
+      mkdir $out
+      # Space-filler to test GC stats reporting
+      head -c 100k /dev/zero > $out/filler
+      echo BAR > $out/bar
+      echo ${input0} > $out/input0
+    '';
+  };
+
+  fod_input = mkDerivation {
+    name = "fod-input";
+    buildCommand = ''
+      echo ${hashInvalidator}
+      echo FOD > $out
+    '';
+    outputHashMode = "flat";
+    outputHashAlgo = "sha256";
+    outputHash = "1dq9p0hnm1y75q2x40fws5887bq1r840hzdxak0a9djbwvx0b16d";
+  };
+
+in
+mkDerivation {
+  name = "dependencies-top";
+  builder = ./dependencies.builder0.sh + "/FOOBAR/../.";
+  input1 = input1 + "/.";
+  input2 = "${input2}/.";
+  input1_drv = input1;
+  input2_drv = input2;
+  input0_drv = input0;
+  fod_input_drv = fod_input;
+  meta.description = "Random test package";
+}

tests/functional2/testlib/utils.py

@@ -1,4 +1,5 @@
 import builtins
+import os
 import types
 import typing
 from pathlib import Path
@@ -10,6 +11,8 @@ from functional2.testlib.fixtures.file_helper import (
     CopyTree,
     FileDeclaration,
     merge_file_declaration,
+    Fileish,
+    CopyTemplate,
 )
 
 # Things have to be resolved from top to bottom, because otherwise the tests behave flakey
@@ -131,3 +134,29 @@ def is_value_of_type(value: Any, expected_type: type[Any] | UnionType) -> bool:
         case _:
             msg = f"Unsupported expected_type. Must be a non-generic or one of {supported_origin_types!r}"
             raise ValueError(msg)
+
+
+def get_global_asset(name: str) -> Fileish:
+    if name == "config.nix":
+        return CopyTemplate(
+            functional2_base_folder / "testlib" / "global_assets" / "config.nix.template",
+            {
+                "system": os.environ.get("system"),  # noqa: SIM112 # system is actually lowercase here
+                # Either just the build shell or entire global path if we are darwin
+                "path": os.environ.get("BUILD_TEST_SHELL") or os.environ.get("PATH"),
+            },
+        )
+    return CopyFile(functional2_base_folder / "testlib" / "global_assets" / name)
+
+
+def get_global_asset_pack(name: Literal["dependencies"]) -> FileDeclaration:
+    match name:
+        case "dependencies":
+            return {
+                "config.nix": get_global_asset("config.nix"),
+                "dependencies.nix": get_global_asset("dependencies.nix"),
+                "dependencies.builder0.sh": get_global_asset("dependencies.builder0.sh"),
+            }
+        case _:
+            msg = f"invalid pack name {name!r}"
+            raise ValueError(msg)