test watch, split commands

flake.nix

@@ -15,11 +15,16 @@
         ./test/it.test.nix
         ./test/test.test.nix
         ./test/describe.test.nix
+        ./test/watch.test.nix
       ];
       packages.x86_64-linux.example = tix.run [
         ./mytest.nix
       ];
       packages.x86_64-linux.watch =
-        tix.watch "nix run .#test --show-trace | ${pkgs.fx}/bin/fx" "fx";
+        tix.watch {
+          cmd = "nix run .#test --show-trace";
+          view = "${pkgs.fx}/bin/fx";
+          stop = "pkill fx";
+        };
     };
 }

test/watch.test.nix

@@ -0,0 +1,52 @@
+{describe, it, ... }:
+let
+  mockpkgs = {
+    writeShellScriptBin = name: content: content;
+    inotify-tools = "inotify-tools";
+  };
+  watch = import ../tix/watch.nix mockpkgs;
+in
+describe "watch" [
+  (it "watches a the local directory and runs command on change" ({
+    actual = watch {
+      cmd = "run me";
+    };
+    expected = ''
+      while true
+      do
+        run me &
+        inotify-tools/bin/inotifywait -e modify -r .
+        
+      done
+    '';
+  }))
+  (it "runs the command provided to stop execution" ({
+    actual = watch {
+      cmd = "run me";
+      stop = "kill me";
+    };
+    expected = ''
+      while true
+      do
+        run me &
+        inotify-tools/bin/inotifywait -e modify -r .
+        kill me
+      done
+    '';
+  }))
+  (it "pipes output to given command" ({
+    actual = watch {
+      cmd = "run me";
+      stop = "kill me";
+      view = "less";
+    };
+    expected = ''
+      while true
+      do
+        run me | less &
+        inotify-tools/bin/inotifywait -e modify -r .
+        kill me
+      done
+    '';
+  }))
+]

tix/watch.nix

@@ -1,9 +1,13 @@
-pkgs: cmd: pname:
+pkgs: {
+  cmd,
+  stop ? null,
+  view ? null,
+}:
 pkgs.writeShellScriptBin "watch" ''
   while true
   do
-    ${cmd} &
+    ${cmd} ${if view == null then "" else "| ${view} "}&
     ${pkgs.inotify-tools}/bin/inotifywait -e modify -r .
-    pkill ${pname}
+    ${toString stop}
   done
 ''