test(config): comprehensive test suite for _apply_env_overrides and from_file (+66 tests)

[manus-use]

Summary

Comprehensive test suite for Config._apply_env_overrides() and Config.from_file() — the untested configuration loading pipeline that maps environment variables to config fields.

What's tested (66 new tests)

MANUS_LLM_* overrides — always-override semantics (12 tests)

• MANUS_LLM_PROVIDER always overrides configured provider
• MANUS_LLM_MODEL always overrides configured model
• MANUS_LLM_BASE_URL always overrides configured base_url
• MANUS_LLM_TEMPERATURE float parsing and override
• MANUS_LLM_MAX_TOKENS int parsing and override
• Empty string treated as unset (no override)

API key resolution — fill-when-None semantics (7 tests)

• OPENAI_API_KEY fills openai provider key only when None
• ANTHROPIC_API_KEY fills anthropic provider key only when None
• Bedrock/Ollama/unknown providers don't get env-based keys
• Explicit config.toml keys are never overwritten by env

AWS region resolution (5 tests)

• Priority: MANUS_AWS_REGION > AWS_DEFAULT_REGION > AWS_REGION
• Returns None when no env vars set
• Config-set region not overwritten

Integration configs (15 tests)

• OTX: MANUS_OTX_API_KEY fill-when-None
• GitHub: MANUS_GITHUB_TOKEN > GITHUB_TOKEN priority
• Lark: MANUS_LARK_API_TOKEN > LARK_API_TOKEN, same for document URL
• Webhooks: MANUS_WEBHOOK_CVE_SUBMIT_URL
• MCP: MANUS_MCP_SERVER_URL

Config.from_file() search paths (7 tests)

• Explicit path loading
• CWD config.toml auto-discovery
• config/config.toml fallback
• ~/.manus-agent/config.toml last resort
• Missing path returns defaults
• All TOML sections loaded correctly

from_file() + env override priority (4 tests)

• Env vars override TOML values for MANUS_LLM_*
• API keys from TOML preserved (fill-when-None)
• API keys absent in TOML filled from env

_load_dotenv() behavior (8 tests)

• CWD .env found and loaded
• config/.env fallback
• ~/.manus-agent/.env fallback
• CWD takes priority over config/
• No .env file doesn't error
• Missing python-dotenv is graceful no-op
• Existing shell vars not overwritten (override=False)

Combined scenarios (3 tests)

• Full env-only configuration (no file)
• Partial env override preserving file values
• Empty env var strings treated as unset

Testing approach

• Pure unit tests with mock.patch.dict(os.environ, ...) for isolation
• tmp_path and monkeypatch.chdir for filesystem tests
• No network calls, no external dependencies
• Tests verify both the documented semantics (always-override vs fill-when-None) and edge cases

Why this matters

_apply_env_overrides() is a Pydantic @model_validator that runs on every Config() construction — it's the central env→config mapping pipeline. Previously untested, meaning:

• Typos in env var names would go undetected
• Priority rule regressions (e.g. env accidentally overwriting explicit config) would be silent
• New integration configs added without env var tests could have broken mappings

All 66 tests pass. No existing tests affected.