add tests for config, fix failing test on Site

In order to do snapshot testing of the site output we want the output to
always be the same regardless of how the filesystem tree was created

.gitignore

@@ -2,3 +2,7 @@
 __pycache__
 *.egg-info
 *.pyc
+.coverage
+htmlcov/
+tests/data/sites/*/output/
+tests/data/sites/*/build.log

Makefile

@@ -0,0 +1,29 @@
+TEST_SITE := tests/data/sites/main
+OUTPUT    := $(TEST_SITE)/output
+
+.PHONY: build build-drafts check test coverage clean serve
+
+build:
+	OSSG_TYPECHECKED="1" ossg --site $(TEST_SITE) -v build
+
+build-drafts:
+	OSSG_TYPECHECKED="1" ossg --site $(TEST_SITE) -v build --drafts
+
+check:
+	mypy -p omicron.ssg
+	black --check omicron tests/unit tests/e2e
+
+test:
+	pytest
+
+coverage:
+	coverage run -m pytest tests/unit
+	coverage report
+	coverage html
+	@echo "file://$(CURDIR)/htmlcov/index.html"
+
+clean:
+	ossg --site $(TEST_SITE) clean
+
+serve:
+	python -m http.server --bind 127.0.0.1 --directory $(OUTPUT)

omicron/ssg/cli.py

@@ -2,7 +2,8 @@ import argparse
 import logging
 import sys
 from omicron.ssg.output import OutputError
-from omicron.ssg.site import ConfigError, Site
+from omicron.ssg.site import Site
+from omicron.ssg.config import ConfigError
 from pathlib import Path
 
 

omicron/ssg/config.py

@@ -0,0 +1,101 @@
+from dataclasses import dataclass
+from pathlib import Path
+import logging
+import yaml
+from urllib.parse import urlparse
+
+log = logging.getLogger(__name__)
+
+
+class ConfigError(RuntimeError):
+    pass
+
+
+DEFAULT_ITEMS_PER_PAGE = 20
+
+
+@dataclass
+class SiteConfig:
+    name: str
+    origin: str
+    base_dir: Path
+    items_per_page: int
+    template: str
+
+    @staticmethod
+    def parse_base_url(value: str | None) -> tuple[str, Path]:
+        if not value:
+            return ("", Path("/"))
+        try:
+            parsed = urlparse(value)
+        except ValueError as e:
+            raise ConfigError("invalid url format in base_url") from e
+        if parsed.scheme and parsed.netloc:
+            origin = f"{parsed.scheme}://{parsed.netloc}"
+        elif parsed.netloc:
+            origin = f"//{parsed.netloc}"
+        else:
+            origin = ""
+
+        if parsed.path:
+            path = Path(parsed.path)
+        else:
+            path = Path("/")
+
+        if not path.is_absolute():
+            raise ConfigError("base_url config property must not be a relative path")
+
+        return (origin, path)
+
+    @staticmethod
+    def from_file(path: Path) -> SiteConfig:
+        log.debug("Reading config file %s", path)
+        try:
+            with open(path, "r") as f:
+                config = yaml.safe_load(f)
+        except FileNotFoundError as e:
+            raise ConfigError("config file missing, not a valid ossg directory") from e
+        except yaml.YAMLError as e:
+            raise ConfigError("config file must be a valid YAML file") from e
+        if not isinstance(config, dict):
+            raise ConfigError(
+                "config file must be a YAML mapping with string keys and int/str values"
+            )
+        for k, v in config.items():
+            if type(k) != str or type(v) not in [str, int]:
+                raise ConfigError(
+                    "config file must be a YAML mapping with string keys and int/str values"
+                )
+        return SiteConfig.from_dict(config)
+
+    @staticmethod
+    def from_dict(config: dict[str, str | int]) -> SiteConfig:
+        name = config.get("name")
+        template = config.get("template")
+        base_url = config.get("base_url")
+        items_per_page = config.get("items_per_page", DEFAULT_ITEMS_PER_PAGE)
+
+        if name is None:
+            raise ConfigError("config file must contain a name property")
+        if template is None:
+            raise ConfigError("config file must contain a template property")
+        if base_url is not None and not isinstance(base_url, str):
+            raise ConfigError("base_url config property must be a string")
+        if not isinstance(name, str):
+            raise ConfigError("name config property must be a string")
+        if not isinstance(template, str):
+            raise ConfigError("template config property must be a string")
+        if not isinstance(items_per_page, int) or items_per_page < 1:
+            raise ConfigError(
+                "items_per_page config property must be a positive integer"
+            )
+
+        origin, base_dir = SiteConfig.parse_base_url(base_url)
+
+        return SiteConfig(
+            name=name,
+            origin=origin,
+            base_dir=base_dir,
+            items_per_page=items_per_page,
+            template=template,
+        )

omicron/ssg/output/directory.py

@@ -14,7 +14,7 @@ else:
 class Directory(Output):
     def __init__(self, site: Site, destination: Path):
         super().__init__(site, destination)
-        url_path = Path("/") / site.base_dir / destination
+        url_path = Path("/") / site.config.base_dir / destination
         # rebuild url because Output strips /index.html which is a valid dir
         self.url = url_path.as_posix()
 

omicron/ssg/output/feed.py

@@ -46,8 +46,9 @@ class Feed(Output):
         return Path(label) / file
 
     def write(self) -> None:
-        feed_url = f"{self.site.origin}{self.url}"
+        config = self.site.config
-        title = f"{self.site.name} — {self.label}" if self.label else self.site.name
+        feed_url = f"{config.origin}{self.url}"
+        title = f"{config.name} — {self.label}" if self.label else config.name
         updated = max(
             (c.updated or c.created for c in self.items), default=date.today()
         )
@@ -60,7 +61,7 @@ class Feed(Output):
 
         for item in self.items:
             entry = SubElement(feed, "entry")
-            item_url = f"{self.site.origin}{item.url}"
+            item_url = f"{config.origin}{item.url}"
             SubElement(entry, "title").text = item.title
             SubElement(entry, "id").text = item_url
             SubElement(entry, "link", href=item_url)

omicron/ssg/output/index.py

@@ -89,14 +89,13 @@ def make_index_pages(
 
 
 def discover_index(site: Site) -> list[Index]:
+    items_per_page = site.config.items_per_page
     outputs: list[Index] = []
-    outputs.extend(
+    outputs.extend(make_index_pages(site, site.content, "root", None, items_per_page))
-        make_index_pages(site, site.content, "root", None, site.items_per_page)
-    )
     for section, items in site.by_section.items():
         outputs.extend(
-            make_index_pages(site, items, "section", section, site.items_per_page)
+            make_index_pages(site, items, "section", section, items_per_page)
         )
     for tag, items in site.by_tag.items():
-        outputs.extend(make_index_pages(site, items, "tag", tag, site.items_per_page))
+        outputs.extend(make_index_pages(site, items, "tag", tag, items_per_page))
     return outputs

omicron/ssg/output/output.py

@@ -26,7 +26,7 @@ class Output(ABC):
             raise OutputError("destination path must be normalized")
         self.destination = destination
 
-        url = site.base_dir / destination
+        url = site.config.base_dir / destination
         if url.name == "index.html":
             url = url.parent
         self.url = url.as_posix()

omicron/ssg/output/sitemap.py

@@ -27,7 +27,7 @@ class Sitemap(Output):
                 continue
 
             url = SubElement(urlset, "url")
-            SubElement(url, "loc").text = f"{self.site.origin}{entry.url}"
+            SubElement(url, "loc").text = f"{self.site.config.origin}{entry.url}"
             if isinstance(entry, Content):
                 lastmod = entry.updated or entry.created
                 SubElement(url, "lastmod").text = lastmod.isoformat()

omicron/ssg/site.py

@@ -1,7 +1,6 @@
 import logging
 import shutil
-from typing import Any, Literal, cast
+from typing import Literal
-from urllib.parse import urlparse
 
 from omicron.ssg.output import (
     Output,
@@ -22,18 +21,14 @@ from omicron.ssg.output import (
     discover_feeds,
 )
 from omicron.ssg.markdown import highlight_style
+from omicron.ssg.config import SiteConfig, ConfigError
 
 from pathlib import Path
-import yaml
 from jinja2 import Environment, FileSystemLoader
 
 log = logging.getLogger(__name__)
 
 
-class ConfigError(RuntimeError):
-    pass
-
-
 class Site:
     def __init__(self, site: Path, drafts: bool = False):
         self.site_path = site.resolve()
@@ -47,50 +42,11 @@ class Site:
         self.by_section: dict[str, list[Content]] = {}
         self.tags_by_count: list[tuple[str, int]] = []
 
-        config = self.read_config()
+        self.config = SiteConfig.from_file(site / "config.yml")
-        self.name: str = config["name"]
+        self.template_path: Path = Site.resolve_template_path(self.config.template)
-        self.template: str = config["template"]
-        self.items_per_page: int = int(config.get("items_per_page", 20))
-        self.origin, self.base_dir = Site.parse_base_url(config.get("base_url"))
-        self.template_path: Path = Site.resolve_template_path(self.template)
         self.output_path: Path = self.site_path / "output"
         self.jinja_env = Environment(loader=FileSystemLoader(self.template_path))
 
-    def read_config(self) -> dict[str, Any]:
-        config_path = self.site_path / "config.yml"
-        log.debug("Reading config file %s", config_path)
-        try:
-            with open(config_path, "r") as f:
-                config = yaml.safe_load(f)
-        except FileNotFoundError:
-            raise ConfigError("config file missing, not a valid ossg directory")
-        if not isinstance(config, dict) or not all(isinstance(k, str) for k in config):
-            raise ConfigError("config file must be a YAML mapping with string keys")
-        if "name" not in config:
-            raise ConfigError("name value missing from config")
-        if "template" not in config:
-            raise ConfigError("template value missing from config")
-        return cast(dict[str, Any], config)
-
-    @staticmethod
-    def parse_base_url(value: str | None) -> tuple[str, Path]:
-        if not value:
-            return ("", Path("/"))
-        parsed = urlparse(value)
-        if parsed.scheme and parsed.netloc:
-            origin = f"{parsed.scheme}://{parsed.netloc}"
-        elif parsed.netloc:
-            origin = f"//{parsed.netloc}"
-        else:
-            origin = ""
-
-        if parsed.path:
-            path = Path(parsed.path)
-        else:
-            path = Path("/")
-
-        return (origin, path)
-
     @staticmethod
     def resolve_template_path(template: str) -> Path:
         path = Path(__file__).parent / "templates" / template
@@ -137,12 +93,12 @@ class Site:
         self.by_source[content.source] = content
 
     def home_url(self) -> str:
-        return self.base_dir.as_posix()
+        return self.config.base_dir.as_posix()
 
     def url_for(self, path: str) -> str:
         if Path(path).is_absolute():
             raise OutputError("path must be relative")
-        return (self.base_dir / path).as_posix()
+        return (self.config.base_dir / path).as_posix()
 
     def section_url(self, section: str) -> str:
         path = Index.build_path("section", 1, section)
@@ -185,7 +141,8 @@ class Site:
         self.other_outputs.append(pygments)
         self.add_by_path(pygments)
         content_path = self.site_path / "content"
-        for file in content_path.rglob("*"):
+        files = sorted(content_path.rglob("*"))
+        for file in files:
             if file.is_file() and is_content(file):
                 content = create_content(self, file)
                 if content.draft and not self.drafts:
@@ -203,7 +160,7 @@ class Site:
         tags_page = discover_tags(self)
         self.add_by_path(tags_page)
         self.other_outputs.append(tags_page)
-        if self.origin:
+        if self.config.origin:
             sitemap = Sitemap(self)
             self.add_by_path(sitemap)
             self.other_outputs.append(sitemap)
@@ -221,13 +178,11 @@ class Site:
         log.info("Removed %s", self.output_path)
 
     def build(self) -> None:
-        if not self.origin:
+        if not self.config.origin:
             log.warning(
                 "base_url config value is missing a domain name, "
                 "can't add canonical url to content"
             )
-        if not self.base_dir.is_absolute():
-            raise ConfigError("base_url config value must be an absolute path")
         self.discover()
         outputs: list[Output] = [*self.directories, *self.content]
         for output in sorted(outputs, key=lambda o: o.destination.as_posix()):

omicron/ssg/templates/plain/article.html

@@ -1,10 +1,10 @@
 {% extends "base.html" %}
 
-{% block title %}{{ page.title }} — {{ site.name }}{% endblock %}
+{% block title %}{{ page.title }} — {{ site.config.name }}{% endblock %}
 
 {% block breadcrumb %}
 <nav aria-label="breadcrumb">
-    <a href="{{ site.home_url() }}">{{ site.name }}</a> ›
+    <a href="{{ site.home_url() }}">{{ site.config.name }}</a> ›
     <a href="{{ site.section_url(page.section) }}">{{ page.section }}</a> ›
     {{ page.title }}
 </nav>

omicron/ssg/templates/plain/base.html

@@ -3,22 +3,22 @@
 <head>
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
-    <title>{% block title %}{{ site.name }}{% endblock %}</title>
+    <title>{% block title %}{{ site.config.name }}{% endblock %}</title>
     <link rel="stylesheet" href="{{ site.url_for('assets/style.css') }}">
     <link rel="stylesheet" href="{{ site.url_for('assets/pygments.css') }}">
-    {% if site.origin %}<link rel="canonical" href="{{ site.origin }}{{ page.url }}">{% endif %}
+    {% if site.config.origin %}<link rel="canonical" href="{{ site.config.origin }}{{ page.url }}">{% endif %}
-    {% if site.feed_url("root", None) %}<link rel="alternate" type="application/atom+xml" title="{{ site.name }}" href="{{ site.feed_url('root', None) }}">{% endif %}
+    {% if site.feed_url("root", None) %}<link rel="alternate" type="application/atom+xml" title="{{ site.config.name }}" href="{{ site.feed_url('root', None) }}">{% endif %}
     {% block head %}{% endblock %}
 </head>
 <body>
     <header>
-        {% block breadcrumb %}<a href="{{ site.home_url() }}">{{ site.name }}</a>{% endblock %}
+        {% block breadcrumb %}<a href="{{ site.home_url() }}">{{ site.config.name }}</a>{% endblock %}
     </header>
     <main>
         {% block main %}{% endblock %}
     </main>
     <footer>
-        <p>{{ site.name }}</p>
+        <p>{{ site.config.name }}</p>
     </footer>
 </body>
 </html>

omicron/ssg/templates/plain/index.html

@@ -1,6 +1,6 @@
 {% extends "base.html" %}
 
-{% block title %}{% if page.label %}{{ page.label }} — {% endif %}{{ site.name }}{% if page.page_num > 1 %} — Page {{ page.page_num }}{% endif %}{% endblock %}
+{% block title %}{% if page.label %}{{ page.label }} — {% endif %}{{ site.config.name }}{% if page.page_num > 1 %} — Page {{ page.page_num }}{% endif %}{% endblock %}
 
 {% block head %}
 {% if page.page_num > 1 %}<meta name="robots" content="noindex, follow">{% endif %}
@@ -12,12 +12,12 @@
 {% block breadcrumb %}
 {% if page.kind == "section" %}
 <nav aria-label="breadcrumb">
-    <a href="{{ site.home_url() }}">{{ site.name }}</a> ›
+    <a href="{{ site.home_url() }}">{{ site.config.name }}</a> ›
     {{ page.label }}
 </nav>
 {% elif page.kind == "tag" %}
 <nav aria-label="breadcrumb">
-    <a href="{{ site.home_url() }}">{{ site.name }}</a> ›
+    <a href="{{ site.home_url() }}">{{ site.config.name }}</a> ›
     <a href="{{ site.tags_url() }}">Tags</a> ›
     {{ page.label }}
 </nav>

omicron/ssg/templates/plain/tags.html

@@ -1,10 +1,10 @@
 {% extends "base.html" %}
 
-{% block title %}Tags — {{ site.name }}{% endblock %}
+{% block title %}Tags — {{ site.config.name }}{% endblock %}
 
 {% block breadcrumb %}
 <nav aria-label="breadcrumb">
-    <a href="{{ site.home_url() }}">{{ site.name }}</a> ›
+    <a href="{{ site.home_url() }}">{{ site.config.name }}</a> ›
     Tags
 </nav>
 {% endblock %}

pyproject.toml

@@ -17,7 +17,9 @@ dependencies = [
 dev = [
     "beartype",
     "black",
+    "coverage",
     "mypy",
+    "pytest",
     "types-PyYAML",
     "types-Pygments",
 ]
@@ -31,6 +33,16 @@ target-version = ["py314"]
 [tool.mypy]
 strict = true
 
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+
+[tool.coverage.run]
+source = ["omicron"]
+
+[tool.coverage.report]
+show_missing = true
+exclude_also = ["@(abc\\.)?abstractmethod"]
+
 [tool.setuptools.packages.find]
 where = ["."]
 include = ["omicron.ssg*"]

tests/data/sites/draft_content/config.yml

@@ -0,0 +1,2 @@
+name: Draft Content Test
+template: plain

tests/data/sites/draft_content/content/draft.md

@@ -0,0 +1,9 @@
+---
+type: article
+section: posts
+slug: draft-post
+title: Draft
+date: 2026-08-28
+draft: true
+---
+Draft.

tests/data/sites/draft_content/content/published.md

@@ -0,0 +1,8 @@
+---
+type: article
+section: posts
+slug: published
+title: Published
+date: 2026-08-28
+---
+Published.

tests/data/sites/duplicate_slug/config.yml

@@ -0,0 +1,2 @@
+name: Duplicate Slug Test
+template: plain

tests/data/sites/duplicate_slug/content/first.md

@@ -0,0 +1,8 @@
+---
+type: article
+section: posts
+slug: hello
+title: First
+date: 2026-08-28
+---
+First.

tests/data/sites/duplicate_slug/content/second.md

@@ -0,0 +1,8 @@
+---
+type: article
+section: posts
+slug: hello
+title: Second
+date: 2026-08-28
+---
+Second.

tests/data/sites/main/config.yml

@@ -0,0 +1,3 @@
+name: Main Test Site
+base_url: http://127.0.0.1:8000
+template: plain

tests/data/sites/main/content/first_post.md

@@ -0,0 +1,10 @@
+---
+type: article
+section: posts
+slug: first-post
+title: First Post
+date: 2026-08-28
+tags: [meta]
+---
+Welcome to the test site. This site will contain some test content for the
+static site generator, the content won't matter a lot.

tests/data/sites/sections/config.yml

@@ -0,0 +1,2 @@
+name: Sections Test
+template: plain

tests/data/sites/sections/content/first-note.md

@@ -0,0 +1,8 @@
+---
+type: article
+section: notes
+slug: first-note
+title: First Note
+date: 2026-08-28
+---
+First note.

tests/data/sites/sections/content/first-post.md

@@ -0,0 +1,8 @@
+---
+type: article
+section: posts
+slug: first-post
+title: First Post
+date: 2026-08-28
+---
+First post.

tests/data/sites/sections/content/second-post.md

@@ -0,0 +1,8 @@
+---
+type: article
+section: posts
+slug: second-post
+title: Second Post
+date: 2026-08-28
+---
+Second post.

tests/data/sites/tags/config.yml

@@ -0,0 +1,2 @@
+name: Tags Test
+template: plain

tests/data/sites/tags/content/no-tags.md

@@ -0,0 +1,8 @@
+---
+type: article
+section: posts
+slug: no-tags
+title: No Tags
+date: 2026-08-28
+---
+No tags.

tests/data/sites/tags/content/one-tag.md

@@ -0,0 +1,9 @@
+---
+type: article
+section: posts
+slug: one-tag
+title: One Tag
+date: 2026-08-28
+tags: [python]
+---
+One tag.

tests/data/sites/tags/content/two-tags.md

@@ -0,0 +1,9 @@
+---
+type: article
+section: posts
+slug: two-tags
+title: Two Tags
+date: 2026-08-28
+tags: [python, testing]
+---
+Two tags.

tests/data/sites/thin_site/config.yml

@@ -0,0 +1,2 @@
+name: test
+template: plain

tests/e2e/test_success.py

@@ -0,0 +1,31 @@
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+
+MAIN_SITE = Path(__file__).parent.parent / "data" / "sites" / "main"
+
+
+@pytest.fixture(scope="module")
+def built_site(tmp_path_factory):
+    site_dir = tmp_path_factory.mktemp("main")
+    shutil.copytree(
+        MAIN_SITE,
+        site_dir,
+        dirs_exist_ok=True,
+        ignore=shutil.ignore_patterns("output", "build.log"),
+    )
+    result = subprocess.run(
+        ["ossg", "--site", str(site_dir), "build"],
+        capture_output=True,
+        text=True,
+    )
+    assert result.returncode == 0, result.stderr
+    return site_dir / "output"
+
+
+def test_article_renders(built_site):
+    output = built_site / "posts" / "first-post" / "index.html"
+    assert output.exists()
+    assert "First Post" in output.read_text()

tests/unit/conftest.py

@@ -0,0 +1,28 @@
+import shutil
+from pathlib import Path
+import pytest
+from omicron.ssg.site import Site
+
+DATA_SITES = Path(__file__).parent.parent / "data" / "sites"
+
+
+@pytest.fixture
+def site_dir(tmp_path):
+    def _make(name):
+        path = tmp_path / name
+        shutil.copytree(
+            DATA_SITES / name,
+            path,
+            ignore=shutil.ignore_patterns("output", "build.log"),
+        )
+        return path
+
+    return _make
+
+
+@pytest.fixture
+def make_site(site_dir):
+    def _make(name, **kwargs):
+        return Site(site_dir(name), **kwargs)
+
+    return _make

tests/unit/test_config.py

@@ -0,0 +1,188 @@
+from pathlib import Path
+import pytest
+from omicron.ssg.config import SiteConfig, ConfigError, DEFAULT_ITEMS_PER_PAGE
+
+
+@pytest.mark.parametrize(
+    "value, expected_origin, expected_path",
+    [
+        (None, "", Path("/")),
+        ("http://example.com/blog", "http://example.com", Path("/blog")),
+        ("http://example.com", "http://example.com", Path("/")),
+        ("//example.com/blog", "//example.com", Path("/blog")),
+        ("/blog", "", Path("/blog")),
+    ],
+)
+def test_parse_base_url(value, expected_origin, expected_path):
+    origin, path = SiteConfig.parse_base_url(value)
+    assert origin == expected_origin
+    assert path == expected_path
+
+
+@pytest.mark.parametrize(
+    "value, expected_message",
+    [
+        ("https://[::1", "invalid url format"),
+        ("relative/path", "relative path"),
+    ],
+)
+def test_parse_base_url_error(value, expected_message):
+    with pytest.raises(ConfigError, match=expected_message):
+        origin, path = SiteConfig.parse_base_url(value)
+
+
+def test_from_dict_minimal():
+    config = SiteConfig.from_dict({"name": "My Site", "template": "plain"})
+
+    assert config.name == "My Site"
+    assert config.template == "plain"
+    assert config.items_per_page == DEFAULT_ITEMS_PER_PAGE
+    assert config.origin == ""
+    assert config.base_dir == Path("/")
+
+
+def test_from_dict_full():
+    config = SiteConfig.from_dict(
+        {
+            "name": "My Site",
+            "template": "plain",
+            "base_url": "http://example.com/blog",
+            "items_per_page": 42,
+        }
+    )
+
+    assert config.name == "My Site"
+    assert config.template == "plain"
+    assert config.items_per_page == 42
+    assert config.origin == "http://example.com"
+    assert config.base_dir == Path("/blog")
+
+
+MISSING = object()
+
+
+@pytest.mark.parametrize(
+    "overrides, expected_message",
+    [
+        ({"name": MISSING}, "must contain a name property"),
+        ({"template": MISSING}, "must contain a template property"),
+        ({"name": 123}, "name config property must be a string"),
+        ({"template": 123}, "template config property must be a string"),
+        ({"base_url": 123}, "base_url config property must be a string"),
+        ({"base_url": "relative/path"}, "relative path"),
+        ({"base_url": "https://[::1"}, "invalid url format"),
+        (
+            {"items_per_page": "10"},
+            "items_per_page config property must be a positive integer",
+        ),
+        (
+            {"items_per_page": 0},
+            "items_per_page config property must be a positive integer",
+        ),
+        (
+            {"items_per_page": -1},
+            "items_per_page config property must be a positive integer",
+        ),
+    ],
+)
+def test_from_dict_error(overrides, expected_message):
+    config = {"name": "My Site", "template": "plain"}
+    for key, value in overrides.items():
+        if value is MISSING:
+            config.pop(key, None)
+        else:
+            config[key] = value
+
+    with pytest.raises(ConfigError, match=expected_message):
+        SiteConfig.from_dict(config)
+
+
+def test_from_file_minimal(tmp_path):
+    path = tmp_path / "config.yml"
+    path.write_text("name: My Site\ntemplate: plain\n")
+
+    config = SiteConfig.from_file(path)
+
+    assert config.name == "My Site"
+    assert config.template == "plain"
+    assert config.items_per_page == DEFAULT_ITEMS_PER_PAGE
+    assert config.origin == ""
+    assert config.base_dir == Path("/")
+
+
+def test_from_file_full(tmp_path):
+    path = tmp_path / "config.yml"
+    path.write_text(
+        "name: My Site\n"
+        "template: plain\n"
+        "base_url: http://example.com/blog\n"
+        "items_per_page: 42\n"
+    )
+
+    config = SiteConfig.from_file(path)
+
+    assert config.name == "My Site"
+    assert config.template == "plain"
+    assert config.items_per_page == 42
+    assert config.origin == "http://example.com"
+    assert config.base_dir == Path("/blog")
+
+
+def test_from_file_missing(tmp_path):
+    path = tmp_path / "config.yml"
+
+    with pytest.raises(ConfigError, match="config file missing"):
+        SiteConfig.from_file(path)
+
+
+@pytest.mark.parametrize(
+    "yaml_text, expected_message",
+    [
+        ("- a\n- b\n", "must be a YAML mapping"),
+        ("just a string\n", "must be a YAML mapping"),
+        ("123: value\n", "must be a YAML mapping"),
+        ("name: [1, 2]\n", "must be a YAML mapping"),
+        ("name: true\n", "must be a YAML mapping"),
+        (":\n  bad: yaml: here\n", "must be a valid YAML file"),
+        ("template: plain\n", "must contain a name property"),
+        ("name: My Site\n", "must contain a template property"),
+        (
+            "name: 123\ntemplate: plain\n",
+            "name config property must be a string",
+        ),
+        (
+            "name: My Site\ntemplate: 123\n",
+            "template config property must be a string",
+        ),
+        (
+            "name: My Site\ntemplate: plain\nbase_url: 123\n",
+            "base_url config property must be a string",
+        ),
+        (
+            "name: My Site\ntemplate: plain\nbase_url: relative/path\n",
+            "relative path",
+        ),
+        (
+            "name: My Site\ntemplate: plain\nbase_url: https://[::1\n",
+            "invalid url format",
+        ),
+        (
+            'name: My Site\ntemplate: plain\nitems_per_page: "10"\n',
+            "items_per_page config property must be a positive integer",
+        ),
+        (
+            "name: My Site\ntemplate: plain\nitems_per_page: 0\n",
+            "items_per_page config property must be a positive integer",
+        ),
+        (
+            "name: My Site\ntemplate: plain\nitems_per_page: -1\n",
+            "items_per_page config property must be a positive integer",
+        ),
+    ],
+)
+def test_from_file_error(tmp_path, yaml_text, expected_message):
+    path = tmp_path / "config.yml"
+    path.write_text(yaml_text)
+
+    with pytest.raises(ConfigError, match=expected_message):
+        SiteConfig.from_file(path)

tests/unit/test_file.py

@@ -0,0 +1,31 @@
+from pathlib import Path
+from omicron.ssg.output.file import File
+
+
+def test_write_copies_content(make_site, tmp_path):
+    site = make_site("thin_site")
+    source = tmp_path / "source.txt"
+    source.write_text("hello")
+    dest_dir = site.output_path / "assets"
+    dest_dir.mkdir(parents=True)
+
+    file = File(site, Path("assets/copy.txt"), source)
+    file.write()
+
+    dest = dest_dir / "copy.txt"
+    assert dest.read_text() == "hello"
+
+
+def test_write_overwrites_existing_destination(make_site, tmp_path):
+    site = make_site("thin_site")
+    dest = site.output_path / "copy.txt"
+    dest.parent.mkdir(parents=True, exist_ok=True)
+    dest.write_text("old")
+
+    source = tmp_path / "source.txt"
+    source.write_text("new")
+
+    file = File(site, Path("copy.txt"), source)
+    file.write()
+
+    assert dest.read_text() == "new"

tests/unit/test_output.py

@@ -0,0 +1,38 @@
+from pathlib import Path
+import pytest
+from omicron.ssg.output.file import File
+from omicron.ssg.output.output import OutputError
+
+
+def test_absolute_destination_raises(make_site, tmp_path):
+    site = make_site("thin_site")
+    with pytest.raises(OutputError):
+        File(site, Path("/copy.txt"), tmp_path / "source.txt")
+
+
+def test_non_normalized_destination_raises(make_site, tmp_path):
+    site = make_site("thin_site")
+    with pytest.raises(OutputError):
+        File(site, Path("assets/../copy.txt"), tmp_path / "source.txt")
+
+
+def test_site_raises_after_garbage_collection(make_site, tmp_path):
+    site = make_site("thin_site")
+    file = File(site, Path("copy.txt"), tmp_path / "source.txt")
+
+    del site
+
+    with pytest.raises(ReferenceError):
+        file.site
+
+
+def test_url(make_site, tmp_path):
+    site = make_site("thin_site")
+    file = File(site, Path("assets/copy.txt"), tmp_path / "source.txt")
+    assert file.url == "/assets/copy.txt"
+
+
+def test_url_strips_index_html(make_site, tmp_path):
+    site = make_site("thin_site")
+    file = File(site, Path("posts/index.html"), tmp_path / "source.txt")
+    assert file.url == "/posts"

tests/unit/test_site.py

@@ -0,0 +1,192 @@
+from pathlib import Path
+import pytest
+from omicron.ssg.output import ContentError, Directory, OutputError
+from omicron.ssg.site import ConfigError, Site
+
+
+def test_discover_raises_on_duplicate_destination(make_site):
+    site = make_site("duplicate_slug")
+    with pytest.raises(ContentError):
+        site.discover()
+
+
+def test_discover_creates_content_directories(make_site):
+    site = make_site("main")
+    site.discover()
+
+    assert isinstance(site.by_path[Path("posts")], Directory)
+    assert isinstance(site.by_path[Path("posts/first-post")], Directory)
+
+
+def test_read_config_errors(site_dir):
+    path = site_dir("thin_site")
+    config_path = path / "config.yml"
+
+    config_path.unlink()
+    with pytest.raises(ConfigError, match="config file missing"):
+        Site(path)
+
+    config_path.write_text("- a\n- b\n")
+    with pytest.raises(ConfigError, match="YAML mapping with string keys"):
+        Site(path)
+
+    config_path.write_text("123: value\n")
+    with pytest.raises(ConfigError, match="YAML mapping with string keys"):
+        Site(path)
+
+    config_path.write_text("template: plain\n")
+    with pytest.raises(ConfigError, match="must contain a name property"):
+        Site(path)
+
+    config_path.write_text("name: test\n")
+    with pytest.raises(ConfigError, match="must contain a template property"):
+        Site(path)
+
+
+def test_site_relative_base_url(site_dir):
+    path = site_dir("thin_site")
+    (path / "config.yml").write_text("name: test\ntemplate: plain\nbase_url: blog\n")
+
+    with pytest.raises(ConfigError, match="relative path"):
+        site = Site(path)
+
+
+def test_discover_skips_drafts_by_default(make_site):
+    site = make_site("draft_content")
+    site.discover()
+
+    assert len(site.content) == 1
+    assert site.content[0].title == "Published"
+
+
+def test_discover_includes_drafts_when_enabled(make_site):
+    site = make_site("draft_content", drafts=True)
+    site.discover()
+
+    assert len(site.content) == 2
+
+
+def test_clean_removes_output_directory(make_site):
+    site = make_site("main")
+    site.build()
+    assert site.output_path.exists()
+
+    site.clean()
+    assert not site.output_path.exists()
+
+    site.clean()
+    assert not site.output_path.exists()
+
+
+def test_resolve_template_path_raises_for_missing_template():
+    with pytest.raises(ConfigError, match="not found"):
+        Site.resolve_template_path("does-not-exist")
+
+
+def test_home_url(site_dir):
+    path = site_dir("thin_site")
+    (path / "config.yml").write_text("name: test\ntemplate: plain\n")
+    assert Site(path).home_url() == "/"
+
+    (path / "config.yml").write_text(
+        "name: test\ntemplate: plain\nbase_url: http://example.com/blog\n"
+    )
+    assert Site(path).home_url() == "/blog"
+
+
+def test_url_for(site_dir):
+    path = site_dir("thin_site")
+    (path / "config.yml").write_text(
+        "name: test\ntemplate: plain\nbase_url: http://example.com/blog\n"
+    )
+
+    site = Site(path)
+    assert site.url_for("assets/style.css") == "/blog/assets/style.css"
+
+    with pytest.raises(OutputError, match="must be relative"):
+        site.url_for("/assets/style.css")
+
+
+def test_section_url(site_dir):
+    path = site_dir("sections")
+
+    site = Site(path)
+    site.discover()
+    assert site.section_url("posts") == "/posts"
+    assert site.section_url("notes") == "/notes"
+
+    (path / "config.yml").write_text("name: test\ntemplate: plain\nbase_url: /blog\n")
+    site = Site(path)
+    site.discover()
+    assert site.section_url("posts") == "/blog/posts"
+    assert site.section_url("notes") == "/blog/notes"
+
+
+def test_add_by_section(make_site):
+    site = make_site("sections")
+    site.discover()
+
+    assert set(site.by_section) == {"posts", "notes"}
+    assert {c.title for c in site.by_section["posts"]} == {"First Post", "Second Post"}
+    assert {c.title for c in site.by_section["notes"]} == {"First Note"}
+
+
+def test_feed_url(site_dir):
+    path = site_dir("tags")
+
+    (path / "config.yml").write_text(
+        "name: test\ntemplate: plain\nbase_url: http://example.com\n"
+    )
+    site = Site(path)
+    site.discover()
+    assert site.feed_url("root", None) == "/atom.xml"
+
+    (path / "config.yml").write_text("name: test\ntemplate: plain\n")
+    site = Site(path)
+    site.discover()
+    assert site.feed_url("root", None) is None
+
+
+def test_tag_url(site_dir):
+    path = site_dir("tags")
+
+    site = Site(path)
+    site.discover()
+    assert site.tag_url("python") == "/tags/python"
+
+    (path / "config.yml").write_text("name: test\ntemplate: plain\nbase_url: /blog\n")
+    site = Site(path)
+    site.discover()
+    assert site.tag_url("python") == "/blog/tags/python"
+
+
+def test_tags_url(make_site):
+    site = make_site("tags")
+    site.discover()
+
+    assert site.tags_url() == "/tags"
+
+
+def test_add_by_source(make_site):
+    site = make_site("tags")
+    site.discover()
+
+    assert site.by_source
+    for content in site.content:
+        assert site.by_source[content.source] is content
+
+
+def test_tags_by_count(make_site):
+    site = make_site("tags")
+    site.discover()
+
+    assert site.tags_by_count == [("python", 2), ("testing", 1)]
+
+
+def test_add_by_tag(make_site):
+    site = make_site("tags")
+    site.discover()
+
+    assert set(site.by_tag) == {"python", "testing"}
+    assert {c.title for c in site.by_tag["python"]} == {"One Tag", "Two Tags"}
+    assert {c.title for c in site.by_tag["testing"]} == {"Two Tags"}