Test against stable versions

Add 2.3 to the flake, and adapt the test to also work with 2.3. Tests
fail, which is expected.

flake.nix

@@ -3,8 +3,10 @@
 
   inputs.nixpkgs.url = "nixpkgs/nixos-21.05-small";
   inputs.lowdown-src = { url = "github:kristapsdz/lowdown"; flake = false; };
+  inputs.nix-2_3-src = { url = "github:nixos/nix/2.3-maintenance"; flake = false; };
+  inputs.nix-2_4 = { url = "github:nixos/nix/2.4-maintenance"; };
 
-  outputs = { self, nixpkgs, lowdown-src }:
+  outputs = { self, nixpkgs, lowdown-src, nix-2_3-src, nix-2_4 }:
 
     let
 
@@ -156,12 +158,7 @@
       testNixVersions = pkgs: client: daemon: with commonDeps pkgs; with pkgs.lib; pkgs.stdenv.mkDerivation {
         NIX_DAEMON_PACKAGE = daemon;
         NIX_CLIENT_PACKAGE = client;
-        name =
-          "nix-tests"
-          + optionalString
-            (versionAtLeast daemon.version "2.4pre20211005" &&
-             versionAtLeast client.version "2.4pre20211005")
-            "-${client.version}-against-${daemon.version}";
+        name = "nix-tests-${client.version}-against-${daemon.version}";
         inherit version;
 
         src = self;
@@ -496,26 +493,45 @@
             '';
         */
 
-        installTests = forAllSystems (system:
-          let pkgs = nixpkgsFor.${system}; in
-          pkgs.runCommand "install-tests" {
-            againstSelf = testNixVersions pkgs pkgs.nix pkgs.pkgs.nix;
-            againstCurrentUnstable =
-              # FIXME: temporarily disable this on macOS because of #3605.
-              if system == "x86_64-linux"
-              then testNixVersions pkgs pkgs.nix pkgs.nixUnstable
-              else null;
-            # Disabled because the latest stable version doesn't handle
-            # `NIX_DAEMON_SOCKET_PATH` which is required for the tests to work
-            # againstLatestStable = testNixVersions pkgs pkgs.nix pkgs.nixStable;
-          } "touch $out");
-
+        installTests = let
+          inherit (nixpkgs) lib;
+          forAllPkgs = f: forAllSystems (system: f nixpkgsFor.${system});
+          allTests = rec {
+            againstSelf = forAllPkgs (pkgs: testNixVersions pkgs pkgs.nix pkgs.pkgs.nix);
+
+            # FIXME: temporarily disable this on macOS because of
+            # #3605. We used to null platforms other than
+            # x86_64-linux, but that broke nix flake check when we
+            # exposed these as standalone hydra jobs.
+            againstCurrentUnstable.x86_64-linux = let
+              pkgs = nixpkgsFor.x86_64-linux;
+            in testNixVersions pkgs pkgs.nix pkgs.nixUnstable;
+
+            againstStable_2_3 = forAllPkgs (pkgs: testNixVersions pkgs pkgs.nix
+              (let
+                pkg = (import "${nix-2_3-src}/release.nix" {
+                  nix = nix-2_3-src;
+                  inherit nixpkgs;
+                  officialRelease = true;
+                }).build.${pkgs.stdenv.hostPlatform.system};
+              in pkg // {
+                inherit (lib.strings.parseDrvName pkg.name) version;
+              }));
+            againstStable_2_4 = forAllPkgs (pkgs: testNixVersions pkgs pkgs.nix
+              nix-2_4.packages.${pkgs.stdenv.hostPlatform.system}.nix);
+          };
+          all = forAllSystems (system:
+            nixpkgsFor.${system}.runCommand
+              "install-tests"
+              (lib.mapAttrs (_: v: v.${system} or null) allTests)
+              "touch $out");
+        in allTests // { inherit all; };
       };
 
       checks = forAllSystems (system: {
         binaryTarball = self.hydraJobs.binaryTarball.${system};
         perlBindings = self.hydraJobs.perlBindings.${system};
-        installTests = self.hydraJobs.installTests.${system};
+        installTests = self.hydraJobs.installTests.all.${system};
       });
 
       packages = forAllSystems (system: {

tests/ca/build-with-garbage-path.sh

@@ -4,7 +4,7 @@
 
 source common.sh
 
-requireDaemonNewerThan "2.4pre20210621"
+requireDaemonVersionAtleast "2.4pre20210621"
 
 # Get the output path of `rootCA`, and put some garbage instead
 outPath="$(nix-build ./content-addressed.nix -A rootCA --no-out-link)"

tests/ca/common.sh

@@ -2,4 +2,6 @@ source ../common.sh
 
 sed -i 's/experimental-features .*/& ca-derivations ca-references/' "$NIX_CONF_DIR"/nix.conf
 
+requireDaemonVersionAtleast "2.4pre"
+
 restartDaemon

tests/ca/duplicate-realisation-in-closure.sh

@@ -1,6 +1,6 @@
 source ./common.sh
 
-requireDaemonNewerThan "2.4pre20210625"
+requireDaemonVersionAtleast "2.4pre20210625"
 
 sed -i 's/experimental-features .*/& ca-derivations ca-references/' "$NIX_CONF_DIR"/nix.conf
 

tests/ca/post-hook.sh

@@ -2,7 +2,7 @@
 
 source common.sh
 
-requireDaemonNewerThan "2.4pre20210626"
+requireDaemonVersionAtleast "2.4pre20210626"
 
 sed -i 's/experimental-features .*/& ca-derivations ca-references nix-command flakes/' "$NIX_CONF_DIR"/nix.conf
 

tests/ca/recursive.sh

@@ -2,7 +2,7 @@
 
 source common.sh
 
-requireDaemonNewerThan "2.4pre20210623"
+requireDaemonVersionAtleast "2.4pre20210623"
 
 sed -i 's/experimental-features .*/& ca-derivations ca-references nix-command flakes/' "$NIX_CONF_DIR"/nix.conf
 

tests/common.sh.in

@@ -92,7 +92,12 @@ startDaemon() {
     # Start the daemon, wait for the socket to appear.  !!!
     # ‘nix-daemon’ should have an option to fork into the background.
     rm -f $NIX_DAEMON_SOCKET_PATH
-    PATH=$DAEMON_PATH nix daemon &
+    local daemonVersion=$($NIX_DAEMON_PACKAGE/bin/nix-daemon --version | cut -d' ' -f3)
+    if isDaemonVersionAtleast 2.4; then
+        PATH=$DAEMON_PATH nix daemon &
+    else
+        PATH=$DAEMON_PATH nix-daemon &
+    fi
     for ((i = 0; i < 30; i++)); do
         if [[ -S $NIX_DAEMON_SOCKET_PATH ]]; then break; fi
         sleep 1
@@ -125,15 +130,16 @@ if [[ $(uname) == Linux ]] && [[ -L /proc/self/ns/user ]] && unshare --user true
     _canUseSandbox=1
 fi
 
-isDaemonNewer () {
+isDaemonVersionAtleast () {
   [[ -n "${NIX_DAEMON_PACKAGE:-}" ]] || return 0
   local requiredVersion="$1"
   local daemonVersion=$($NIX_DAEMON_PACKAGE/bin/nix-daemon --version | cut -d' ' -f3)
   [[ $(nix eval --expr "builtins.compareVersions ''$daemonVersion'' ''$requiredVersion''") -ge 0 ]]
 }
 
-requireDaemonNewerThan () {
-  isDaemonNewer "$1" || exit 99
+requireDaemonVersionAtleast () {
+  echo "Daemon is too old for this test, skipping..."
+  isDaemonVersionAtleast "$1" || exit 99
 }
 
 canUseSandbox() {

tests/fixed.sh

@@ -15,7 +15,7 @@ nix path-info --json $path | grep fixed:md5:2qk15sxzzjlnpjk9brn7j8ppcd
 echo 'testing good...'
 nix-build fixed.nix -A good --no-out-link
 
-if isDaemonNewer "2.4pre20210927"; then
+if isDaemonVersionAtleast "2.4pre20210927"; then
     echo 'testing --check...'
     nix-build fixed.nix -A check --check && fail "should fail"
 fi

tests/recursive.sh

@@ -8,11 +8,17 @@ if [[ $(uname) != Linux ]]; then exit 99; fi
 
 clearStore
 
-rm -f $TEST_ROOT/result
+rm -f "$TEST_ROOT/result"
 
-export unreachable=$(nix store add-path ./recursive.sh)
+export unreachable
+unreachable=$(nix store add-path ./recursive.sh)
 
-NIX_BIN_DIR=$(dirname $(type -p nix)) nix --extra-experimental-features 'nix-command recursive-nix' build -o $TEST_ROOT/result -L --impure --expr '
+requiredSystemFeatures=()
+if isDaemonVersionAtleast "2.4pre"; then
+    requiredSystemFeatures+=(recursive-nix)
+fi
+
+NIX_BIN_DIR=$(dirname "$(type -p nix)") nix --extra-experimental-features 'nix-command recursive-nix' build -o "$TEST_ROOT/result" -L --impure --expr '
   with import ./config.nix;
   mkDerivation rec {
     name = "recursive";
@@ -24,7 +30,7 @@ NIX_BIN_DIR=$(dirname $(type -p nix)) nix --extra-experimental-features 'nix-com
 
     NIX_TESTS_CA_BY_DEFAULT = builtins.getEnv "NIX_TESTS_CA_BY_DEFAULT";
 
-    requiredSystemFeatures = [ "recursive-nix" ];
+    requiredSystemFeatures = [ '"$(printf '"%s" ' "${requiredSystemFeatures[@]}")"'];
 
     buildCommand = '\'\''
       mkdir $out
@@ -70,9 +76,9 @@ NIX_BIN_DIR=$(dirname $(type -p nix)) nix --extra-experimental-features 'nix-com
   }
 '
 
-[[ $(cat $TEST_ROOT/result/inner1) =~ blaat ]]
+[[ "$(cat "$TEST_ROOT/result/inner1")" =~ blaat ]]
 
 # Make sure the recursively created paths are in the closure.
-nix path-info -r $TEST_ROOT/result | grep foobar
-nix path-info -r $TEST_ROOT/result | grep fnord
-nix path-info -r $TEST_ROOT/result | grep inner1
+nix path-info -r "$TEST_ROOT/result" | grep foobar
+nix path-info -r "$TEST_ROOT/result" | grep fnord
+nix path-info -r "$TEST_ROOT/result" | grep inner1

tests/structured-attrs.sh

@@ -2,7 +2,7 @@ source common.sh
 
 # 27ce722638 required some incompatible changes to the nix file, so skip this
 # tests for the older versions
-requireDaemonNewerThan "2.4pre20210712"
+requireDaemonVersionAtleast "2.4pre20210712"
 
 clearStore