Switch CI to Nix flakes

We also move tests to Flakes.

This would allow users to submit PRs with a fork of nixpkgs when they
want to test nixpkgs PRs against SNM.

tests/clamav.nix

@@ -14,19 +14,12 @@
 #  You should have received a copy of the GNU General Public License
 #  along with this program. If not, see <http://www.gnu.org/licenses/>
 
-{ pkgs ? import <nixpkgs> {}}:
+{ pkgs ? import <nixpkgs> {}, blobs}:
 
 pkgs.nixosTest {
   name = "clamav";
   nodes = {
     server = { config, pkgs, lib, ... }:
-      let
-        sources = import ../nix/sources.nix;
-        blobs = pkgs.fetchzip {
-          url = sources.blobs.url;
-          sha256 = sources.blobs.sha256;
-        };
-      in
         {
             imports = [
                 ../default.nix

tests/default.nix

@@ -1,48 +0,0 @@
-# Generate an attribute sets containing all tests for all releaeses
-# It looks like:
-# - external.nixpkgs_20.03
-# - external.nixpkgs_unstable
-# - internal.nixpkgs_20.03
-# - internal.nixpkgs_unstable
-
-with builtins;
-
-let
-  sources = import ../nix/sources.nix;
-
-  releases = listToAttrs (map genRelease releaseNames);
-
-  genRelease = name: {
-    name = name;
-    value = import sources."${name}" {};
-  };
-
-  genTest = testName: release:
-  let
-    pkgs = releases."${release}";
-    test = pkgs.callPackage (./. + "/${testName}.nix") { };
-  in {
-    "name"= builtins.replaceStrings ["." "-"] ["_" "_"] release;
-    "value"= test;
-  };
-
-  releaseNames = [
-    "nixpkgs-unstable"
-    "nixpkgs-20.09"
-    "nixpkgs-21.05"
-  ];
-
-  testNames = [
-    "internal"
-    "external"
-    "clamav"
-    "multiple"
-  ];
-
-  # Generate an attribute set containing one test per releases
-  genTests = testName: {
-    name = testName;
-    value = listToAttrs (map (genTest testName) (builtins.attrNames releases));
-  };
-  
-in listToAttrs (map genTests testNames)

tests/external.nix

@@ -14,7 +14,7 @@
 #  You should have received a copy of the GNU General Public License
 #  along with this program. If not, see <http://www.gnu.org/licenses/>
 
-{ pkgs ? import <nixpkgs> {}}:
+{ pkgs ? import <nixpkgs> {}, ...}:
 
 pkgs.nixosTest {
   name = "external";

tests/internal.nix

@@ -14,7 +14,7 @@
 #  You should have received a copy of the GNU General Public License
 #  along with this program. If not, see <http://www.gnu.org/licenses/>
 
-{ pkgs ? import <nixpkgs> {}}:
+{ pkgs ? import <nixpkgs> {}, ...}:
 
 let
   sendMail = pkgs.writeTextFile {

tests/multiple.nix

@@ -1,6 +1,6 @@
 # This tests is used to test features requiring several mail domains.
 
-{ pkgs ? import <nixpkgs> {}}:
+{ pkgs ? import <nixpkgs> {}, ...}:
 
 let
     hashPassword = password: pkgs.runCommand