feat: Improved variable handling for config

This allows an environment variable in any position for headers as long
as it is in format `$VAR` or `${VAR}` allowing alphanumeric characters
and underscore `_`. This is now also applied to `remote_schema_url` in
addition to headers.

Fixes #328
Relates to #231

Author: bombsimon

ariadne_codegen/settings.py

@@ -1,5 +1,6 @@
 import enum
 import os
+import re
 from dataclasses import dataclass, field
 from keyword import iskeyword
 from pathlib import Path
@@ -50,6 +51,7 @@ def __post_init__(self):
             assert_path_exists(self.schema_path)
 
         self.remote_schema_headers = resolve_headers(self.remote_schema_headers)
+        self.remote_schema_url = resolve_schema(self.remote_schema_url)
 
 
 @dataclass
@@ -276,20 +278,29 @@ def assert_string_is_valid_python_identifier(name: str):
 def resolve_headers(headers: Dict) -> Dict:
     return {key: get_header_value(value) for key, value in headers.items()}
 
+def resolve_schema(value: str) -> str:
+    return _replace_env_vars(value)
+
 
 def get_header_value(value: str) -> str:
-    env_var_prefix = "$"
-    if value.startswith(env_var_prefix):
-        env_var_name = value.lstrip(env_var_prefix)
+    return _replace_env_vars(value)
+
+
+def _replace_env_vars(value: str) -> str:
+    pattern = re.compile(r"\${?([\w_]+)}?")
+
+    def replacer(match):
+        env_var_name = match.group(1)
         var_value = os.environ.get(env_var_name)
+
         if not var_value:
             raise InvalidConfiguration(
                 f"Environment variable {env_var_name} not found."
             )
-        return var_value
 
-    return value
+        return var_value
 
+    return pattern.sub(replacer, value)
 
 def assert_class_is_defined_in_file(file_path: Path, class_name: str):
     file_content = file_path.read_text()

tests/test_settings.py

@@ -133,8 +133,24 @@ def test_client_settings_without_schema_path_or_remote_schema_url_raises_excepti
         ClientSettings(queries_path=queries_path)
 
 
+@pytest.mark.parametrize(
+    "configured_header, expected_header",
+    [
+        ("$TEST_VAR", "test_value"),
+        ("Bearer: $TEST_VAR", "Bearer: test_value"),
+        ("Bearer: ${TEST_VAR}", "Bearer: test_value"),
+        pytest.param(
+            "$NOT_SET_VAR",
+            "",
+            marks=pytest.mark.xfail(raises=InvalidConfiguration),
+        ),
+    ],
+)
 def test_client_settings_resolves_env_variable_for_remote_schema_header_with_prefix(
-    tmp_path, mocker
+    tmp_path,
+    mocker,
+    configured_header,
+    expected_header,
 ):
     queries_path = tmp_path / "queries.graphql"
     queries_path.touch()
@@ -143,10 +159,42 @@ def test_client_settings_resolves_env_variable_for_remote_schema_header_with_pre
     settings = ClientSettings(
         queries_path=queries_path,
         remote_schema_url="https://test",
-        remote_schema_headers={"Authorization": "$TEST_VAR"},
+        remote_schema_headers={"Authorization": configured_header},
+    )
+
+    assert settings.remote_schema_headers["Authorization"] == expected_header
+
+
+@pytest.mark.parametrize(
+    "configured_url, expected_url",
+    [
+        ("$TEST_VAR", "test_value"),
+        ("https://${TEST_VAR}/graphql", "https://test_value/graphql"),
+        ("https://$TEST_VAR/graphql", "https://test_value/graphql"),
+        ("https://TEST_VAR/graphql", "https://TEST_VAR/graphql"),
+        pytest.param(
+            "https://${NOT_SET_VAR}/graphql",
+            "",
+            marks=pytest.mark.xfail(raises=InvalidConfiguration),
+        ),
+    ],
+)
+def test_client_settings_resolves_env_variable_for_remote_schema(
+    tmp_path,
+    mocker,
+    configured_url,
+    expected_url,
+):
+    queries_path = tmp_path / "queries.graphql"
+    queries_path.touch()
+    mocker.patch.dict(os.environ, {"TEST_VAR": "test_value"})
+
+    settings = ClientSettings(
+        queries_path=queries_path,
+        remote_schema_url=configured_url,
     )
 
-    assert settings.remote_schema_headers["Authorization"] == "test_value"
+    assert settings.remote_schema_url == expected_url
 
 
 def test_client_settings_doesnt_resolve_remote_schema_header_without_prefix(tmp_path):