feat: add automatic API key detection from DECART_API_KEY env var

decart/client.py

@@ -1,3 +1,4 @@
+import os
 from typing import Any, Optional
 import aiohttp
 from pydantic import ValidationError
@@ -20,14 +21,18 @@ class DecartClient:
     Decart API client for video and image generation/transformation.
 
     Args:
-        api_key: Your Decart API key
+        api_key: Your Decart API key. Defaults to the DECART_API_KEY environment variable.
         base_url: API base URL (defaults to production)
         integration: Optional integration identifier (e.g., "langchain/0.1.0")
 
     Example:
         ```python
+        # Option 1: Explicit API key
         client = DecartClient(api_key="your-key")
 
+        # Option 2: Using DECART_API_KEY environment variable
+        client = DecartClient()
+
         # Image generation (sync) - use process()
         image = await client.process({
             "model": models.image("lucy-pro-t2i"),
@@ -44,17 +49,19 @@ class DecartClient:
 
     def __init__(
         self,
-        api_key: str,
+        api_key: Optional[str] = None,
         base_url: str = "https://api.decart.ai",
         integration: Optional[str] = None,
     ) -> None:
-        if not api_key or not api_key.strip():
+        resolved_api_key = api_key or os.environ.get("DECART_API_KEY", "").strip() or None
+
+        if not resolved_api_key:
             raise InvalidAPIKeyError()
 
         if not base_url.startswith(("http://", "https://")):
             raise InvalidBaseURLError(base_url)
 
-        self.api_key = api_key
+        self.api_key = resolved_api_key
         self.base_url = base_url
         self.integration = integration
         self._session: Optional[aiohttp.ClientSession] = None

decart/errors.py

@@ -26,7 +26,9 @@ class InvalidAPIKeyError(DecartSDKError):
     """Raised when API key is invalid or missing."""
 
     def __init__(self) -> None:
-        super().__init__("API key is required and must be a non-empty string")
+        super().__init__(
+            "Missing API key. Pass `api_key` to DecartClient() or set the DECART_API_KEY environment variable."
+        )
 
 
 class InvalidBaseURLError(DecartSDKError):

tests/test_client.py

@@ -2,23 +2,59 @@
 from decart import DecartClient, InvalidAPIKeyError, InvalidBaseURLError
 
 
-def test_create_client_success() -> None:
-    client = DecartClient(api_key="test-key")
-    assert client is not None
-    assert client.process is not None
-
-
-def test_create_client_invalid_api_key() -> None:
-    with pytest.raises(InvalidAPIKeyError):
-        DecartClient(api_key="")
-
-
-def test_create_client_invalid_base_url() -> None:
-    with pytest.raises(InvalidBaseURLError):
-        DecartClient(api_key="test-key", base_url="invalid-url")
-
-
-def test_create_client_custom_base_url() -> None:
-    client = DecartClient(api_key="test-key", base_url="https://custom.decart.ai")
-    assert client is not None
-    assert client.base_url == "https://custom.decart.ai"
+class TestDecartClient:
+    """Tests for DecartClient initialization."""
+
+    def test_create_client_with_explicit_api_key(self) -> None:
+        """Creates a client with explicit api_key."""
+        client = DecartClient(api_key="test-key")
+        assert client is not None
+        assert client.process is not None
+        assert client.api_key == "test-key"
+
+    def test_create_client_from_env_var(self, monkeypatch: pytest.MonkeyPatch) -> None:
+        """Creates a client using DECART_API_KEY env var."""
+        monkeypatch.setenv("DECART_API_KEY", "env-api-key")
+        client = DecartClient()
+        assert client is not None
+        assert client.api_key == "env-api-key"
+
+    def test_explicit_api_key_takes_precedence(self, monkeypatch: pytest.MonkeyPatch) -> None:
+        """Explicit api_key takes precedence over env var."""
+        monkeypatch.setenv("DECART_API_KEY", "env-api-key")
+        client = DecartClient(api_key="explicit-key")
+        assert client.api_key == "explicit-key"
+
+    def test_create_client_no_api_key_no_env(self, monkeypatch: pytest.MonkeyPatch) -> None:
+        """Throws an error if api key is not provided and env var is not set."""
+        monkeypatch.delenv("DECART_API_KEY", raising=False)
+        with pytest.raises(InvalidAPIKeyError, match="Missing API key"):
+            DecartClient()
+
+    def test_create_client_empty_api_key(self) -> None:
+        """Throws an error if api key is empty string."""
+        with pytest.raises(InvalidAPIKeyError, match="Missing API key"):
+            DecartClient(api_key="")
+
+    def test_create_client_empty_env_var(self, monkeypatch: pytest.MonkeyPatch) -> None:
+        """Throws an error if env var is empty string."""
+        monkeypatch.setenv("DECART_API_KEY", "")
+        with pytest.raises(InvalidAPIKeyError, match="Missing API key"):
+            DecartClient()
+
+    def test_create_client_whitespace_env_var(self, monkeypatch: pytest.MonkeyPatch) -> None:
+        """Throws an error if env var is only whitespace."""
+        monkeypatch.setenv("DECART_API_KEY", "   ")
+        with pytest.raises(InvalidAPIKeyError, match="Missing API key"):
+            DecartClient()
+
+    def test_create_client_invalid_base_url(self) -> None:
+        """Throws an error if invalid base url is provided."""
+        with pytest.raises(InvalidBaseURLError):
+            DecartClient(api_key="test-key", base_url="invalid-url")
+
+    def test_create_client_custom_base_url(self) -> None:
+        """Creates a client with custom base url."""
+        client = DecartClient(api_key="test-key", base_url="https://custom.decart.ai")
+        assert client is not None
+        assert client.base_url == "https://custom.decart.ai"