Make src_paths behave as expected when using --resolve-all-configs

When using `--resolve-all-configs`, there is unexpected behavior in that
`src_paths` ends up resolving relative to the project root, which
defaults to the current working directory. This results in first-party
modules being marked as third-party modules in the default case.

Under the previous implementation, one possible workaround would be to
specify the relative path to config directory (e.g.
`relative/path/to/configdir/src`). However, assuming that the most
common use of `--resolve-all-configs` is to support multiple
sub-projects in the same repository/overall directory, this workaround
would now require each sub-project to understand where it lives in the
filesystem.

This change proposes a fix that sets `directory` on the `config_data` to
be the directory containing the used configuration file if not already
set. Downstream, this directory is then used to resolve the absolute
paths specified by `src_paths`.

Fixes PyCQA#2045

docs/configuration/options.md

@@ -1758,7 +1758,7 @@ Explicitly set the config root for resolving all configs. When used with the --r
 
 ## Resolve All Configs
 
-Tells isort to resolve the configs for all sub-directories and sort files in terms of its closest config files.
+Tells isort to resolve the configs for all sub-directories and sort files in terms of its closest config files. When using this option, `src_paths` will resolve relative to the directory that contains the config that was used by default.
 
 **Type:** Bool  
 **Default:** `False`  

isort/settings.py

@@ -820,6 +820,8 @@ def find_all_configs(path: str) -> Trie:
                     config_data = {}
 
                 if config_data:
+                    if "directory" not in config_data:
+                        config_data["directory"] = dirpath
                     trie_root.insert(potential_config_file, config_data)
                     break
 

tests/unit/test_settings.py

@@ -241,6 +241,7 @@ def test_find_all_configs(tmpdir):
     pyproject_toml = """
 [tool.isort]
 profile = "hug"
+src_paths = ["src"]
 """
 
     isort_cfg = """
@@ -280,14 +281,18 @@ def test_find_all_configs(tmpdir):
     config_info_1 = config_trie.search(str(dir1 / "test1.py"))
     assert config_info_1[0] == str(setup_cfg_file)
     assert config_info_1[0] == str(setup_cfg_file) and config_info_1[1]["profile"] == "django"
+    assert set(Config(**config_info_1[1]).src_paths) == {Path(dir1), Path(dir1, "src")}
 
     config_info_2 = config_trie.search(str(dir2 / "test2.py"))
     assert config_info_2[0] == str(pyproject_toml_file)
     assert config_info_2[0] == str(pyproject_toml_file) and config_info_2[1]["profile"] == "hug"
+    assert set(Config(**config_info_2[1]).src_paths) == {Path(dir2, "src")}
 
     config_info_3 = config_trie.search(str(dir3 / "test3.py"))
     assert config_info_3[0] == str(isort_cfg_file)
     assert config_info_3[0] == str(isort_cfg_file) and config_info_3[1]["profile"] == "black"
+    assert set(Config(**config_info_3[1]).src_paths) == {Path(dir3), Path(dir3, "src")}
 
     config_info_4 = config_trie.search(str(tmpdir / "file4.py"))
     assert config_info_4[0] == "default"
+    assert set(Config(**config_info_4[1]).src_paths) == {Path.cwd(), Path.cwd().joinpath("src")}