nix-gc: rename frequency to dates

modules/services/nix-gc.nix

@@ -5,7 +5,7 @@
   ...
 }:
 let
-  inherit (lib) mkOption types;
+  inherit (lib) mkChangedOptionModule mkOption types;
 
   cfg = config.nix.gc;
 
@@ -15,6 +15,12 @@ in
 {
   meta.maintainers = [ lib.maintainers.shivaraj-bh ];
 
+  imports = [
+    (mkChangedOptionModule [ "nix" "gc" "frequency" ] [ "nix" "gc" "dates" ] (
+      config: lib.toList (lib.getAttrFromPath [ "nix" "gc" "frequency" ] config)
+    ))
+  ];
+
   options = {
     nix.gc = {
       automatic = mkOption {
@@ -27,8 +33,9 @@ in
         '';
       };
 
-      frequency = mkOption {
-        type = types.str;
+      dates = mkOption {
+        type = with types; either singleLineStr (listOf str);
+        apply = lib.toList;
         default = "weekly";
         example = "03:15";
         description = ''
@@ -97,7 +104,7 @@ in
             Description = "Nix Garbage Collector";
           };
           Timer = {
-            OnCalendar = "${cfg.frequency}";
+            OnCalendar = cfg.dates;
             RandomizedDelaySec = cfg.randomizedDelaySec;
             Persistent = cfg.persistent;
             Unit = "nix-gc.service";
@@ -110,7 +117,11 @@ in
 
       (lib.mkIf pkgs.stdenv.isDarwin {
         assertions = [
-          (lib.hm.darwin.assertInterval "nix.gc.frequency" cfg.frequency pkgs)
+          {
+            assertion = (lib.length cfg.dates) == 1;
+            message = "On Darwin, `nix.gc.dates` must contain a single element.";
+          }
+          (lib.hm.darwin.assertInterval "nix.gc.dates.*" (lib.elemAt cfg.dates 0) pkgs)
         ];
 
         launchd.agents.nix-gc = {
@@ -120,7 +131,7 @@ in
               "${nixPackage}/bin/nix-collect-garbage"
             ]
             ++ lib.optional (cfg.options != null) cfg.options;
-            StartCalendarInterval = lib.hm.darwin.mkCalendarInterval cfg.frequency;
+            StartCalendarInterval = lib.hm.darwin.mkCalendarInterval (lib.elemAt cfg.dates 0);
           };
         };
       })

tests/modules/services/nix-gc/darwin/basic.nix

@@ -1,7 +1,7 @@
 {
   nix.gc = {
     automatic = true;
-    frequency = "monthly";
+    dates = "monthly";
     options = "--delete-older-than 30d";
   };
 

tests/modules/services/nix-gc/darwin/changed-options.nix

@@ -0,0 +1,21 @@
+{ lib, options, ... }:
+
+{
+  nix.gc = {
+    automatic = true;
+    frequency = "monthly";
+    options = "--delete-older-than 30d";
+  };
+
+  test.asserts.warnings.expected = [
+    "The option `nix.gc.frequency' defined in ${lib.showFiles options.nix.gc.frequency.files} has been changed to `nix.gc.dates' that has a different type. Please read `nix.gc.dates' documentation and update your configuration accordingly."
+  ];
+
+  nmt.script = ''
+    serviceFile=LaunchAgents/org.nix-community.home.nix-gc.plist
+
+    assertFileExists "$serviceFile"
+
+    assertFileContent "$serviceFile" ${./expected-agent.plist}
+  '';
+}

tests/modules/services/nix-gc/darwin/darwin-nix-gc-interval-assertion.nix

@@ -1,10 +1,10 @@
 {
   nix.gc = {
     automatic = true;
-    frequency = "00:02:03";
+    dates = "00:02:03";
   };
 
   test.asserts.assertions.expected = [
-    "On Darwin nix.gc.frequency must be one of: hourly, daily, weekly, monthly, semiannually, annually."
+    "On Darwin nix.gc.dates.* must be one of: hourly, daily, weekly, monthly, semiannually, annually."
   ];
 }

tests/modules/services/nix-gc/darwin/default.nix

@@ -1,4 +1,5 @@
 {
   nix-gc = ./basic.nix;
   nix-gc-interval-assertion = ./darwin-nix-gc-interval-assertion.nix;
+  nix-gc-changed-options = ./changed-options.nix;
 }

tests/modules/services/nix-gc/linux/basic.nix

@@ -1,7 +1,7 @@
 {
   nix.gc = {
     automatic = true;
-    frequency = "monthly";
+    dates = [ "monthly" ];
     randomizedDelaySec = "42min";
     options = "--delete-older-than 30d --max-freed $((64 * 1024**3))";
   };

tests/modules/services/nix-gc/linux/changed-options.nix

@@ -0,0 +1,43 @@
+{ lib, options, ... }:
+
+{
+  nix.gc = {
+    automatic = true;
+    frequency = "monthly";
+    randomizedDelaySec = "42min";
+    options = "--delete-older-than 30d --max-freed $((64 * 1024**3))";
+  };
+
+  test.asserts.warnings.expected = [
+    "The option `nix.gc.frequency' defined in ${lib.showFiles options.nix.gc.frequency.files} has been changed to `nix.gc.dates' that has a different type. Please read `nix.gc.dates' documentation and update your configuration accordingly."
+  ];
+
+  nmt.script = ''
+    serviceFile=home-files/.config/systemd/user/nix-gc.service
+
+    assertFileExists $serviceFile
+
+    serviceFile=$(normalizeStorePaths $serviceFile)
+
+    assertFileContent $serviceFile ${./expected.service}
+
+    timerFile=home-files/.config/systemd/user/nix-gc.timer
+
+    assertFileExists $timerFile
+
+    timerFile=$(normalizeStorePaths $timerFile)
+
+    assertFileContent $timerFile ${./expected.timer}
+
+    nixgcScriptFile=$(grep -o \
+      '/nix/store/.*-nix-gc' \
+      $TESTED/home-files/.config/systemd/user/nix-gc.service
+    )
+
+    assertFileExists $nixgcScriptFile
+
+    nixgcScriptFile=$(normalizeStorePaths $nixgcScriptFile)
+
+    assertFileContent $nixgcScriptFile ${./nix-gc-script-expected}
+  '';
+}

tests/modules/services/nix-gc/linux/default.nix

@@ -1,3 +1,4 @@
 {
   nix-gc = ./basic.nix;
+  nix-gc-changed-options = ./changed-options.nix;
 }