fix: restore testing framework to actually work (#2070)

after refactor to some new asynchronous items for finders,
the tests stopped actually doing anything.

now they do things again.

lua/telescope/testharness/init.lua

@@ -0,0 +1,112 @@
+local assert = require "luassert"
+
+local Path = require "plenary.path"
+
+local tester = {}
+tester.debug = false
+
+local get_results_from_contents = function(content)
+  local nvim = vim.fn.jobstart(
+    { "nvim", "--noplugin", "-u", "scripts/minimal_init.vim", "--headless", "--embed" },
+    { rpc = true }
+  )
+
+  local result = vim.fn.rpcrequest(nvim, "nvim_exec_lua", content, {})
+  assert.are.same(true, result[1], vim.inspect(result))
+
+  local count = 0
+  while
+    vim.fn.rpcrequest(nvim, "nvim_exec_lua", "return require('telescope.testharness.runner').state.done", {}) ~= true
+  do
+    count = count + 1
+    vim.wait(100)
+
+    -- TODO: Could maybe wait longer, but it's annoying to wait if the test is going to timeout.
+    if count > 100 then
+      break
+    end
+  end
+
+  local state = vim.fn.rpcrequest(nvim, "nvim_exec_lua", "return require('telescope.testharness.runner').state", {})
+  vim.fn.jobstop(nvim)
+
+  assert.are.same(true, state.done, vim.inspect(state))
+
+  local result_table = {}
+  for _, v in ipairs(state.results) do
+    table.insert(result_table, v)
+  end
+
+  return result_table, state
+end
+
+local check_results = function(results, state)
+  assert(state, "Must pass state")
+
+  for _, v in ipairs(results) do
+    local assertion
+    if not v._type or v._type == "are" or v._type == "_default" then
+      assertion = assert.are.same
+    else
+      assertion = assert.are_not.same
+    end
+
+    -- TODO: I think it would be nice to be able to see the state,
+    -- but it clutters up the test output so much here.
+    --
+    -- So we would have to consider how to do that I think.
+    assertion(v.expected, v.actual, string.format("Test Case: %s // %s", v.location, v.case))
+  end
+end
+
+tester.run_string = function(contents)
+  contents = [[
+    return (function()
+      local tester = require('telescope.testharness')
+      local runner = require('telescope.testharness.runner')
+      local helper = require('telescope.testharness.helpers')
+      helper.make_globals()
+      local ok, msg = pcall(function()
+        runner.log("Loading Test")
+        ]] .. contents .. [[
+      end)
+      return {ok, msg or runner.state}
+    end)()
+  ]]
+
+  check_results(get_results_from_contents(contents))
+end
+
+tester.run_file = function(filename)
+  local file = "./lua/tests/pickers/" .. filename .. ".lua"
+  local path = Path:new(file)
+
+  if not path:exists() then
+    assert.are.same("<An existing file>", file)
+  end
+
+  local contents = string.format(
+    [[
+    return (function()
+      local runner = require('telescope.testharness.runner')
+      local helper = require('telescope.testharness.helpers')
+      helper.make_globals()
+      local ok, msg = pcall(function()
+        runner.log("Loading Test")
+        return loadfile("%s")()
+      end)
+      return {ok, msg or runner.state}
+    end)()
+  ]],
+    path:absolute()
+  )
+
+  check_results(get_results_from_contents(contents))
+end
+
+tester.not_ = function(val)
+  val._type = "are_not"
+  return val
+end
+
+return tester