init .config git tracking

config/fish/functions/gtest.fish

@@ -0,0 +1,21 @@
+# gtest: test a command against git staged changes.
+#
+# example usage:
+#   gtest make test
+function gtest -d "test command on staged changes only"
+  # Stash working dir, keeping index changes.
+  git stash push -q --keep-index --include-untracked; or return
+
+  # Run test command against index changes only.
+  command $argv
+  set cmdstatus $status
+
+  # Return working dir and index to original state.
+  # Note: reset + restore is required to prevent merge conflicts
+  # when popping the stash.
+  git reset -q
+  git restore .
+  git stash pop -q --index; or return $status
+
+  return $cmdstatus
+end