Jobset: test type-related constraints

Prior to https://github.com/NixOS/hydra/pull/856, the `type`-related constraints
were a bit too loose, allowing some variations that should have been seen as
invalid. This commit adds a test (inspired by
https://github.com/NixOS/hydra/pull/856#issuecomment-772820929) to ensure these
constraints stay unviolated.

t/Controller/Jobset/type-constraints.t

@@ -0,0 +1,122 @@
+use strict;
+use Setup;
+my %ctx = test_init();
+
+require Hydra::Schema;
+require Hydra::Model::DB;
+require Hydra::Helper::Nix;
+
+use Data::Dumper;
+use Test2::V0;
+use Test2::Compare qw(compare strict_convert);
+
+my $db = Hydra::Model::DB->new;
+hydra_setup($db);
+
+# This test checks a matrix of jobset configuration options for constraint violations.
+
+my @types = ( 0, 1, 2 );
+my @nixexprinputs = ( undef, "input" );
+my @nixexprpaths = ( undef, "path" );
+my @flakes = ( undef, "flake" );
+
+my @expected_failing;
+my @expected_succeeding = (
+    {
+        "name" => "test",
+        "emailoverride" => "",
+        "type" => 0,
+        "nixexprinput" => "input",
+        "nixexprpath" => "path",
+        "flake" => undef,
+    },
+    {
+        "name" => "test",
+        "emailoverride" => "",
+        "type" => 1,
+        "nixexprinput" => undef,
+        "nixexprpath" => undef,
+        "flake" => "flake",
+    },
+);
+
+# Checks if two Perl hashes (in scalar context) contain the same data.
+# Returns 0 if they are different and 1 if they are the same.
+sub test_scenario_matches {
+    my ($first, $second) = @_;
+
+    my $ret = compare($first, $second, \&strict_convert);
+
+    if (defined $ret == 1) {
+        return 0;
+    } else {
+        return 1;
+    }
+}
+
+# Construct a matrix of parameters that should violate the Jobsets table's constraints.
+foreach my $type (@types) {
+    foreach my $nixexprinput (@nixexprinputs) {
+        foreach my $nixexprpath (@nixexprpaths) {
+            foreach my $flake (@flakes) {
+                my $hash = {
+                    "name" => "test",
+                    "emailoverride" => "",
+                    "type" => $type,
+                    "nixexprinput" => $nixexprinput,
+                    "nixexprpath" => $nixexprpath,
+                    "flake" => $flake,
+                };
+
+                push(@expected_failing, $hash) if (!grep { test_scenario_matches($_, $hash) } @expected_succeeding);
+            };
+        };
+    };
+};
+
+my $project = $db->resultset('Projects')->create({name => "tests", displayname => "", owner => "root"});
+
+# Validate that the list of parameters that should fail the constraints do indeed fail.
+subtest "Expected constraint failures" => sub {
+    my $count = 1;
+    foreach my $case (@expected_failing) {
+        subtest "Case $count: " . Dumper ($case) => sub {
+            dies {
+                # Necessary, otherwise cases will fail because the `->create`
+                # will throw an exception due to an expected constraint failure
+                # (which will cause the `ok()` to be skipped, leading to no
+                # assertions in the subtest).
+                is(1, 1);
+
+                ok(
+                    !$project->jobsets->create($case),
+                    "Expected jobset to violate constraints"
+                );
+            };
+        };
+
+        $count++;
+    };
+};
+
+# Validate that the list of parameters that should not fail the constraints do indeed succeed.
+subtest "Expected constraint successes" => sub {
+    my $count = 1;
+    foreach my $case (@expected_succeeding) {
+        subtest "Case $count: " . Dumper ($case) => sub {
+            my $jobset = $project->jobsets->create($case);
+
+            ok(
+                $jobset,
+                "Expected jobset to not violate constraints"
+            );
+
+            # Delete the jobset so the next jobset won't violate the name constraint.
+            $jobset->delete;
+        };
+
+        $count++;
+    };
+};
+
+done_testing;