Test using Hydra with flakes

It seemed there was no self-contained end-to-end test actually doing
this?!

Among other things, this will help ensure that the switch-over to
`nix-eval-jobs` is correct.

t/evaluator/evaluate-flake.t

@@ -0,0 +1,67 @@
+use feature 'unicode_strings';
+use strict;
+use warnings;
+use Setup;
+use Test2::V0;
+use File::Copy qw(cp);
+
+my $ctx = test_context(
+    nix_config => qq|
+    experimental-features = nix-command flakes
+    |,
+    hydra_config => q|
+    <runcommand>
+      evaluator_pure_eval = false
+    </runcommand>
+    |
+);
+
+sub checkFlake {
+    my ($flake) = @_;
+
+    cp($ctx->jobsdir . "/basic.nix", $ctx->jobsdir . "/" . $flake);
+    cp($ctx->jobsdir . "/config.nix", $ctx->jobsdir . "/" . $flake);
+    cp($ctx->jobsdir . "/empty-dir-builder.sh", $ctx->jobsdir . "/" . $flake);
+    cp($ctx->jobsdir . "/fail.sh", $ctx->jobsdir . "/" . $flake);
+    cp($ctx->jobsdir . "/succeed-with-failed.sh", $ctx->jobsdir . "/" . $flake);
+
+    chmod 0755, $ctx->jobsdir . "/" . $flake . "/empty-dir-builder.sh";
+    chmod 0755, $ctx->jobsdir . "/" . $flake . "/fail.sh";
+    chmod 0755, $ctx->jobsdir . "/" . $flake . "/succeed-with-failed.sh";
+
+    my $builds = $ctx->makeAndEvaluateJobset(
+        flake => 'path:' . $ctx->jobsdir . "/" . $flake,
+        build => 1
+    );
+
+    subtest "Build: succeed_with_failed" => sub {
+        my $build = $builds->{"succeed_with_failed"};
+
+        is($build->finished, 1, "Build should be finished.");
+        is($build->buildstatus, 6, "succeeeded-but-failed should have buildstatus 6.");
+    };
+
+    subtest "Build: empty_dir" => sub {
+        my $build = $builds->{"empty_dir"};
+
+        is($build->finished, 1, "Build should be finished.");
+        is($build->buildstatus, 0, "Should have succeeded.");
+    };
+
+    subtest "Build: fails" => sub {
+        my $build = $builds->{"fails"};
+
+        is($build->finished, 1, "Build should be finished.");
+        is($build->buildstatus, 1, "Should have failed.");
+    };
+}
+
+subtest "Flake using `checks`" => sub {
+    checkFlake 'flake-checks'
+};
+
+subtest "Flake using `hydraJobs`" => sub {
+    checkFlake 'flake-hydraJobs'
+};
+
+done_testing;

t/jobs/flake-checks/flake.nix

@@ -0,0 +1,6 @@
+{
+  outputs = { ... }: {
+    checks =
+      import ./basic.nix;
+  };
+}

t/jobs/flake-hydraJobs/flake.nix

@@ -0,0 +1,6 @@
+{
+  outputs = { ... }: {
+    hydraJobs =
+      import ./basic.nix;
+  };
+}

t/lib/HydraTestContext.pm

@@ -165,14 +165,25 @@ sub nix_state_dir {
 sub makeAndEvaluateJobset {
     my ($self, %opts) = @_;
 
-    my $expression = $opts{'expression'} || die "Mandatory 'expression' option not passed to makeAndEvaluateJobset.\n";
+    my $expression = $opts{'expression'};
+    my $flake = $opts{'flake'};
+    if (not $expression and not $flake) {
+        die "One of 'expression' or 'flake' must be passed to makeEvaluateJobset.\n";
+    }
+
     my $jobsdir = $opts{'jobsdir'} // $self->jobsdir;
     my $should_build = $opts{'build'} // 0;
 
-    my $jobsetCtx = $self->makeJobset(
-        expression => $expression,
+    my %args = (
         jobsdir => $jobsdir,
     );
+    if ($expression) {
+        $args{expression} = $expression;
+    }
+    if ($flake) {
+        $args{flake} = $flake;
+    }
+    my $jobsetCtx = $self->makeJobset(%args);
     my $jobset = $jobsetCtx->{"jobset"};
 
     evalSucceeds($jobset) or die "Evaluating jobs/$expression should exit with return code 0.\n";
@@ -195,7 +206,7 @@ sub makeAndEvaluateJobset {
 #
 # In return, you get a hash of the user, project, and jobset records.
 #
-# This always uses an `expression` from the `jobsdir` directory.
+# This always uses an `expression` or `flake` from the `jobsdir` directory.
 #
 # Hash Parameters:
 #
@@ -204,7 +215,12 @@ sub makeAndEvaluateJobset {
 sub makeJobset {
     my ($self, %opts) = @_;
 
-    my $expression = $opts{'expression'} || die "Mandatory 'expression' option not passed to makeJobset.\n";
+    my $expression = $opts{'expression'};
+    my $flake = $opts{'flake'};
+    if (not $expression and not $flake) {
+        die "One of 'expression' or 'flake' must be passed to makeJobset.\n";
+    }
+
     my $jobsdir = $opts{'jobsdir'} // $self->jobsdir;
 
     # Create a new user for this test
@@ -222,12 +238,20 @@ sub makeJobset {
     });
 
     # Create a new jobset for this test and set up the inputs
-    my $jobset = $project->jobsets->create({
+    my %args = (
         name => rand_chars(),
-        nixexprinput => "jobs",
-        nixexprpath => $expression,
         emailoverride => ""
-    });
+    );
+    if ($expression) {
+        $args{type} = 0;
+        $args{nixexprinput} = "jobs";
+        $args{nixexprpath} = $expression;
+    }
+    if ($flake) {
+        $args{type} = 1;
+        $args{flake} = $flake;
+    }
+    my $jobset = $project->jobsets->create(\%args);
     my $jobsetinput = $jobset->jobsetinputs->create({name => "jobs", type => "path"});
     $jobsetinput->jobsetinputalts->create({altnr => 0, value => $jobsdir});