Move MockConfigLoader to OSS (#1324)

Summary:
Pull Request resolved: #1324

1. harding coding "/tmp/model.pt" in config caused race condition when multiple tests are running concurrently
2. we patched the output path with "/tmp{RANDOM_HASH}/model.pt" by MockConfigLoader
3. I want to reuse the same patch logic in OSS integration tests

Differential Revision: D21084986

fbshipit-source-id: 400f6d43a134e189bb2adb1ae4a13a592df1ba7b

Author: hudeven

pytext/utils/config_utils.py

@@ -0,0 +1,61 @@
+#!/usr/bin/env python3
+# Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved
+
+import json
+import os
+from importlib import import_module
+
+from pytext.config import PyTextConfig, config_to_json
+from pytext.config.config_adapter import upgrade_to_latest
+from pytext.config.serialize import pytext_config_from_json
+from pytext.utils.file_io import PathManager
+
+
+class MockConfigLoader:
+    def __init__(
+        self,
+        config_base_path: str,
+        reset_paths: {str: str} = None,
+        replace_paths: {str: str} = None,
+    ):
+        self.config_base_path = config_base_path
+        self.reset_paths = reset_paths or {}
+        self.replace_paths = replace_paths or {}
+
+    def make_config(self, config_filename, disable_tensorboard=True):
+        with PathManager.open(
+            os.path.join(self.config_base_path, config_filename)
+        ) as config_file:
+            # load config json file into dict
+            config_dict = json.load(config_file)
+            if "config" in config_dict:
+                config_dict = config_dict["config"]
+            return self.make_config_from_dict(config_dict, disable_tensorboard)
+
+    def make_config_from_dict(self, config, disable_tensorboard):
+        # config is the path module name of the actual PyText config
+        if isinstance(config, str):
+            config = config_to_json(PyTextConfig, import_module(config).config)
+        config = upgrade_to_latest(config)
+        # Disable TensorBoard for integration tests
+        if disable_tensorboard:
+            config["use_tensorboard"] = False
+        return self.disable_cuda(self.fix_paths(config))
+
+    def disable_cuda(self, config):
+        config["use_cuda_if_available"] = False
+        if "distributed_world_size" in config:
+            del config["distributed_world_size"]
+        return config
+
+    def fix_paths(self, config):
+        if isinstance(config, str):
+            for src, dest in self.replace_paths.items():
+                config = config.replace(src, dest)
+            return config
+        elif isinstance(config, dict):
+            return {key: self.fix_paths(value) for key, value in config.items()}
+        elif isinstance(config, list):
+            return [self.fix_paths(element) for element in config]
+        else:
+            return config