feat: add download target type for fetching files from URLs

tests/test_builder.py

@@ -5,7 +5,7 @@ from __future__ import annotations
 from collections.abc import Callable
 from pathlib import Path
 from typing import override
-from unittest.mock import patch
+from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
 
@@ -16,7 +16,7 @@ from hokusai.builder import (
     _resolve_prompt,  # pyright: ignore[reportPrivateUsage]
     run_build,
 )
-from hokusai.config import ProjectConfig, TargetConfig
+from hokusai.config import GenerateTargetConfig, ProjectConfig
 from hokusai.providers import Provider
 from hokusai.providers.models import Capability, ModelInfo
 from hokusai.state import load_state
@@ -57,7 +57,7 @@ class FakeTextProvider(Provider):
     async def generate(
         self,
         target_name: str,
-        target_config: TargetConfig,
+        target_config: GenerateTargetConfig,
         resolved_prompt: str,
         resolved_model: ModelInfo,
         project_dir: Path,
@@ -78,7 +78,7 @@ class FakeImageProvider(Provider):
     async def generate(
         self,
         target_name: str,
-        target_config: TargetConfig,
+        target_config: GenerateTargetConfig,
         resolved_prompt: str,
         resolved_model: ModelInfo,
         project_dir: Path,
@@ -99,7 +99,7 @@ class FailingTextProvider(Provider):
     async def generate(
         self,
         target_name: str,
-        target_config: TargetConfig,
+        target_config: GenerateTargetConfig,
         resolved_prompt: str,
         resolved_model: ModelInfo,
         project_dir: Path,
@@ -295,7 +295,7 @@ class TestRunBuild:
 
         async def selective_generate(
             target_name: str,
-            target_config: TargetConfig,
+            target_config: GenerateTargetConfig,
             resolved_prompt: str,
             resolved_model: ModelInfo,
             project_dir: Path,
@@ -426,3 +426,145 @@ class TestRunBuild:
 
         assert set(result.built) == {"left.md", "right.md", "merge.txt"}
         assert result.failed == {}
+
+
+class TestDownloadTarget:
+    """Tests for download-type targets that fetch files from URLs."""
+
+    async def test_download_target_fetches_url(
+        self, project_dir: Path, write_config: WriteConfig
+    ) -> None:
+        config = write_config(
+            {
+                "targets": {
+                    "fish.png": {"download": "https://example.com/fish.png"},
+                }
+            }
+        )
+        mock_response = MagicMock()
+        mock_response.content = b"fake image bytes"
+        mock_response.raise_for_status = MagicMock()
+
+        with (
+            patch("hokusai.builder._create_providers", return_value=_fake_providers()),
+            patch("hokusai.builder.httpx.AsyncClient") as mock_client_cls,
+        ):
+            mock_client = AsyncMock()
+            mock_client.get = AsyncMock(return_value=mock_response)
+            mock_client.__aenter__ = AsyncMock(return_value=mock_client)
+            mock_client.__aexit__ = AsyncMock(return_value=False)
+            mock_client_cls.return_value = mock_client
+
+            result = await run_build(config, project_dir, _PROJECT)
+
+        assert result.built == ["fish.png"]
+        assert (project_dir / "fish.png").read_bytes() == b"fake image bytes"
+        mock_client.get.assert_called_once_with(  # pyright: ignore[reportAny]
+            "https://example.com/fish.png", follow_redirects=True
+        )
+
+    async def test_download_target_incremental_skip(
+        self, project_dir: Path, write_config: WriteConfig
+    ) -> None:
+        config = write_config(
+            {
+                "targets": {
+                    "fish.png": {"download": "https://example.com/fish.png"},
+                }
+            }
+        )
+        mock_response = MagicMock()
+        mock_response.content = b"fake image bytes"
+        mock_response.raise_for_status = MagicMock()
+
+        with (
+            patch("hokusai.builder._create_providers", return_value=_fake_providers()),
+            patch("hokusai.builder.httpx.AsyncClient") as mock_client_cls,
+        ):
+            mock_client = AsyncMock()
+            mock_client.get = AsyncMock(return_value=mock_response)
+            mock_client.__aenter__ = AsyncMock(return_value=mock_client)
+            mock_client.__aexit__ = AsyncMock(return_value=False)
+            mock_client_cls.return_value = mock_client
+
+            r1 = await run_build(config, project_dir, _PROJECT)
+            assert r1.built == ["fish.png"]
+
+            r2 = await run_build(config, project_dir, _PROJECT)
+            assert r2.skipped == ["fish.png"]
+            assert r2.built == []
+
+    async def test_download_target_rebuild_on_url_change(
+        self, project_dir: Path, write_config: WriteConfig
+    ) -> None:
+        config1 = write_config(
+            {
+                "targets": {
+                    "fish.png": {"download": "https://example.com/fish-v1.png"},
+                }
+            }
+        )
+        mock_response = MagicMock()
+        mock_response.content = b"v1 bytes"
+        mock_response.raise_for_status = MagicMock()
+
+        with (
+            patch("hokusai.builder._create_providers", return_value=_fake_providers()),
+            patch("hokusai.builder.httpx.AsyncClient") as mock_client_cls,
+        ):
+            mock_client = AsyncMock()
+            mock_client.get = AsyncMock(return_value=mock_response)
+            mock_client.__aenter__ = AsyncMock(return_value=mock_client)
+            mock_client.__aexit__ = AsyncMock(return_value=False)
+            mock_client_cls.return_value = mock_client
+
+            r1 = await run_build(config1, project_dir, _PROJECT)
+            assert r1.built == ["fish.png"]
+
+            config2 = write_config(
+                {
+                    "targets": {
+                        "fish.png": {"download": "https://example.com/fish-v2.png"},
+                    }
+                }
+            )
+            mock_response.content = b"v2 bytes"
+
+            r2 = await run_build(config2, project_dir, _PROJECT)
+            assert r2.built == ["fish.png"]
+            assert (project_dir / "fish.png").read_bytes() == b"v2 bytes"
+
+    async def test_download_target_as_dependency(
+        self, project_dir: Path, write_config: WriteConfig
+    ) -> None:
+        config = write_config(
+            {
+                "targets": {
+                    "fish.png": {"download": "https://example.com/fish.png"},
+                    "description.txt": {
+                        "prompt": "Describe the fish",
+                        "inputs": ["fish.png"],
+                    },
+                }
+            }
+        )
+        mock_response = MagicMock()
+        mock_response.content = b"fake fish image"
+        mock_response.raise_for_status = MagicMock()
+
+        with (
+            patch("hokusai.builder._create_providers", return_value=_fake_providers()),
+            patch("hokusai.builder.httpx.AsyncClient") as mock_client_cls,
+        ):
+            mock_client = AsyncMock()
+            mock_client.get = AsyncMock(return_value=mock_response)
+            mock_client.__aenter__ = AsyncMock(return_value=mock_client)
+            mock_client.__aexit__ = AsyncMock(return_value=False)
+            mock_client_cls.return_value = mock_client
+
+            result = await run_build(config, project_dir, _PROJECT)
+
+        assert "fish.png" in result.built
+        assert "description.txt" in result.built
+        assert (project_dir / "fish.png").read_bytes() == b"fake fish image"
+        assert (project_dir / "description.txt").exists()