feat(vim): add go to spec plugin

This will find the spec file that is associated to the current source
file.

site-modules/core/files/vim/plugin/spec.lua

@@ -0,0 +1,82 @@
+local alternate_type = {
+  SPEC = "spec",
+}
+
+local alternates = {
+  -- Market dojo spec files for components. We need to remove the component
+  -- directory to map them to the correct folder map.
+  ["app/javascript/components/(.*)%.(jsx?)$"] = {
+    { type = alternate_type.SPEC, file = "spec/react/%1.spec.%2", default = true },
+  },
+  -- Market dojo spec files for other javascript stuff
+  ["app/javascript/(.*)%.(jsx?)$"] = {
+    { type = alternate_type.SPEC, file = "spec/react/%1.spec.%2", default = true },
+  },
+  -- Map js/ts files to spec files from the application dir
+  ["app/(.*)%.([jt]sx?)$"] = {
+    { type = alternate_type.SPEC, file = "spec/%1.test.%2" },
+    { type = alternate_type.SPEC, file = "test/%1.test.%2" },
+    { type = alternate_type.SPEC, file = "tests/%1.test.%2" },
+    { type = alternate_type.SPEC, file = "spec/%1.spec.%2" },
+    { type = alternate_type.SPEC, file = "tests/%1.spec.%2", default = true },
+  },
+  -- Map js/ts files to spec files from the source dir
+  ["src/(.*)%.([jt]sx?)$"] = {
+    { type = alternate_type.SPEC, file = "spec/%1.test.%2" },
+    { type = alternate_type.SPEC, file = "test/%1.test.%2" },
+    { type = alternate_type.SPEC, file = "tests/%1.test.%2" },
+    { type = alternate_type.SPEC, file = "spec/%1.spec.%2" },
+    { type = alternate_type.SPEC, file = "tests/%1.spec.%2", default = true },
+  },
+}
+
+local function file_exists(filename)
+  local file = io.open(filename, "r")
+  if file then
+    io.close(file)
+    return true
+  else
+    return false
+  end
+end
+
+local function find_alt(
+  _, --[[ type ]]
+  file_name
+)
+  local default_alternate = nil
+
+  for key, match_list in pairs(alternates) do
+    for _, match in ipairs(match_list) do
+      local alternate, found = string.gsub(file_name, key, match.file)
+      if found > 0 then
+        if file_exists(alternate) then
+          return alternate
+        elseif match.default then
+          default_alternate = alternate
+        end
+      end
+    end
+
+    -- Return the first default match we find.
+    if default_alternate ~= nil then
+      return default_alternate
+    end
+  end
+
+  -- Not alternative found
+  return nil
+end
+
+vim.api.nvim_create_user_command("GoToSpec", function()
+  local buffer_name = vim.fn.fnamemodify(vim.fn.expand "%", ":p:~:.")
+  local spec = find_alt(nil, buffer_name)
+  if spec ~= nil then
+    vim.cmd("edit " .. spec)
+    return
+  end
+
+  print("ERR: No alternate file found for " .. buffer_name)
+end, { bang = true, desc = "Go to the spec file for the current buffer" })
+
+vim.keymap.set("n", "gs", ":GoToSpec<CR>", { silent = true })