Add compile-time link validation for blog post internal links

- Add Blogex.LinkValidator module to validate /blog/{id}/{slug} semantics - Add Blogex.LinkError exception with actionable error messages - Integrate validation into Blogex.Blog via @before_compile callback - Add unit tests (34) and integration tests (4) for link validation - Add test fixtures (valid/invalid posts) in blogex/priv/blog/test/ Closes: validate-internal-link-semantics-in-blog-post-markdown-bodies-at-compile-time-h3hb Closes: define-link-semantic-validation-logic-in-blogex-7syv Closes: write-tests-for-link-semantic-validation-y30h Closes: integrate-link-validation-into-blogexblog-compile-time-macro-1205
2026-05-07 11:56:54 +01:00
parent c535e63b70
commit ab7a520e9e
7 changed files with 679 additions and 0 deletions
@@ -0,0 +1,96 @@
+defmodule Blogex.BlogIntegrationTest do
+  use ExUnit.Case
+
+  describe "compile-time link validation" do
+    test "raises LinkError for invalid blog ID in link" do
+      tmp_file = Path.join(System.tmp_dir!(), "test_blog_invalid.ex")
+
+      File.write!(tmp_file, """
+      defmodule TestBlogInvalidBlogId do
+        use Blogex.Blog,
+          blog_id: :test,
+          app: :blogex,
+          from: "priv/blog/test/2026/01-02-invalid-post.md",
+          title: "Test Blog",
+          base_path: "/blog/test"
+      end
+      """)
+
+      assert_raise Blogex.LinkError, fn ->
+        Code.compile_file(tmp_file, __ENV__.file)
+      end
+
+      File.rm!(tmp_file)
+    end
+
+    test "raises LinkError for invalid slug in link" do
+      tmp_file = Path.join(System.tmp_dir!(), "test_blog_invalid_slug.ex")
+
+      File.write!(tmp_file, """
+      defmodule TestBlogInvalidSlug do
+        use Blogex.Blog,
+          blog_id: :test,
+          app: :blogex,
+          from: "priv/blog/test/2026/01-02-invalid-post.md",
+          title: "Test Blog",
+          base_path: "/blog/test"
+      end
+      """)
+
+      assert_raise Blogex.LinkError, fn ->
+        Code.compile_file(tmp_file, __ENV__.file)
+      end
+
+      File.rm!(tmp_file)
+    end
+
+    test "compiles successfully with valid links" do
+      tmp_file = Path.join(System.tmp_dir!(), "test_blog_valid.ex")
+
+      File.write!(tmp_file, """
+      defmodule TestBlogValid do
+        use Blogex.Blog,
+          blog_id: :test,
+          app: :blogex,
+          from: "priv/blog/test/2026/01-01-valid-post.md",
+          title: "Test Blog",
+          base_path: "/blog/test"
+      end
+      """)
+
+      [{TestBlogValid, _bytecode}] = Code.compile_file(tmp_file, __ENV__.file)
+      assert TestBlogValid.title() == "Test Blog"
+
+      File.rm!(tmp_file)
+    end
+
+    test "LinkError message includes post context" do
+      tmp_file = Path.join(System.tmp_dir!(), "test_blog_msg.ex")
+
+      File.write!(tmp_file, """
+      defmodule TestBlogErrorMsg do
+        use Blogex.Blog,
+          blog_id: :test,
+          app: :blogex,
+          from: "priv/blog/test/2026/01-02-invalid-post.md",
+          title: "Test Blog",
+          base_path: "/blog/test"
+      end
+      """)
+
+      exception =
+        assert_raise Blogex.LinkError, fn ->
+          Code.compile_file(tmp_file, __ENV__.file)
+        end
+
+      msg = Exception.message(exception)
+
+      assert msg =~ "invalid internal blog links"
+      assert msg =~ "invalid-post"
+      assert msg =~ "/blog/unknown/broken"
+      assert msg =~ "/blog/engineering/My-Post"
+
+      File.rm!(tmp_file)
+    end
+  end
+end
@@ -0,0 +1,236 @@
+defmodule Blogex.LinkValidatorTest do
+  use ExUnit.Case
+  alias Blogex.LinkValidator
+
+  describe "extract_links/1" do
+    test "extracts internal blog links from markdown body" do
+      body =
+        "<p>Check out [hello world](/blog/engineering/hello-world) and [release v1](/blog/releases/v1-0-0).</p>"
+
+      assert LinkValidator.extract_links(body) == [
+               "/blog/engineering/hello-world",
+               "/blog/releases/v1-0-0"
+             ]
+    end
+
+    test "ignores external links" do
+      body = "<p>See [GitHub](https://github.com) and [internal](/blog/engineering/post).</p>"
+
+      assert LinkValidator.extract_links(body) == ["/blog/engineering/post"]
+    end
+
+    test "ignores non-blog internal links" do
+      body = "<p>See [/about](/about) and [/blog/engineering/post](/blog/engineering/post).</p>"
+
+      assert LinkValidator.extract_links(body) == ["/blog/engineering/post"]
+    end
+
+    test "returns empty list when no internal blog links" do
+      body = "<p>Just external links: [GitHub](https://github.com).</p>"
+
+      assert LinkValidator.extract_links(body) == []
+    end
+
+    test "handles multiple links on one line" do
+      body = "<p>[a](/blog/engineering/a) [b](/blog/releases/b) [c](/blog/engineering/c)</p>"
+
+      assert LinkValidator.extract_links(body) == [
+               "/blog/engineering/a",
+               "/blog/releases/b",
+               "/blog/engineering/c"
+             ]
+    end
+
+    test "handles links with query strings" do
+      body = "<p>[link](/blog/engineering/post?foo=bar)</p>"
+
+      assert LinkValidator.extract_links(body) == ["/blog/engineering/post?foo=bar"]
+    end
+
+    test "handles links with anchor fragments" do
+      body = "<p>[link](/blog/engineering/post#section)</p>"
+
+      assert LinkValidator.extract_links(body) == ["/blog/engineering/post#section"]
+    end
+
+    test "handles empty body" do
+      assert LinkValidator.extract_links("") == []
+    end
+  end
+
+  describe "validate_link/1" do
+    test "validates correct engineering link" do
+      assert LinkValidator.validate_link("/blog/engineering/my-post") == :ok
+    end
+
+    test "validates correct releases link" do
+      assert LinkValidator.validate_link("/blog/releases/v1-0-0") == :ok
+    end
+
+    test "rejects unknown blog ID" do
+      assert LinkValidator.validate_link("/blog/unknown/post") ==
+               {:error, "unknown blog ID: unknown"}
+    end
+
+    test "rejects uppercase blog ID" do
+      assert LinkValidator.validate_link("/blog/Engineering/post") ==
+               {:error, "unknown blog ID: Engineering"}
+    end
+
+    test "rejects empty slug" do
+      assert LinkValidator.validate_link("/blog/engineering/") ==
+               {:error, "empty slug"}
+    end
+
+    test "rejects slug with uppercase letters" do
+      assert LinkValidator.validate_link("/blog/engineering/My-Post") ==
+               {:error, "slug must be lowercase alphanumeric with hyphens: My-Post"}
+    end
+
+    test "rejects slug with special characters" do
+      assert LinkValidator.validate_link("/blog/engineering/hello@world") ==
+               {:error, "slug must be lowercase alphanumeric with hyphens: hello@world"}
+    end
+
+    test "rejects slug with spaces" do
+      assert LinkValidator.validate_link("/blog/engineering/hello world") ==
+               {:error, "slug must be lowercase alphanumeric with hyphens: hello world"}
+    end
+
+    test "allows single-word slug" do
+      assert LinkValidator.validate_link("/blog/engineering/hello") == :ok
+    end
+
+    test "allows hyphenated slug" do
+      assert LinkValidator.validate_link("/blog/engineering/my-cool-post") == :ok
+    end
+
+    test "allows slug with numbers" do
+      assert LinkValidator.validate_link("/blog/releases/v1-2-3") == :ok
+    end
+
+    test "rejects slug starting with hyphen" do
+      assert LinkValidator.validate_link("/blog/engineering/-post") ==
+               {:error, "slug must be lowercase alphanumeric with hyphens: -post"}
+    end
+
+    test "rejects slug ending with hyphen" do
+      assert LinkValidator.validate_link("/blog/engineering/post-") ==
+               {:error, "slug must be lowercase alphanumeric with hyphens: post-"}
+    end
+
+    test "rejects consecutive hyphens" do
+      assert LinkValidator.validate_link("/blog/engineering/post--name") ==
+               {:error, "slug must be lowercase alphanumeric with hyphens: post--name"}
+    end
+
+    test "returns :ok for link with query string and valid slug" do
+      assert LinkValidator.validate_link("/blog/engineering/post?foo=bar") == :ok
+    end
+
+    test "returns :ok for link with anchor fragment and valid slug" do
+      assert LinkValidator.validate_link("/blog/engineering/post#section") == :ok
+    end
+
+    test "rejects non-blog path" do
+      assert LinkValidator.validate_link("/about") ==
+               {:error, "not a blog link: /about"}
+    end
+
+    test "rejects malformed link" do
+      assert LinkValidator.validate_link("not-a-url") ==
+               {:error, "not a blog link: not-a-url"}
+    end
+  end
+
+  describe "validate_links/1" do
+    test "returns :ok when all links are valid" do
+      links = [
+        "/blog/engineering/hello-world",
+        "/blog/releases/v1-0-0"
+      ]
+
+      assert LinkValidator.validate_links(links) == :ok
+    end
+
+    test "returns errors for invalid links" do
+      links = [
+        "/blog/engineering/hello-world",
+        "/blog/unknown/post",
+        "/blog/releases/My-Post"
+      ]
+
+      assert LinkValidator.validate_links(links) == {
+               :error,
+               [
+                 {2, "/blog/unknown/post", "unknown blog ID: unknown"},
+                 {3, "/blog/releases/My-Post",
+                  "slug must be lowercase alphanumeric with hyphens: My-Post"}
+               ]
+             }
+    end
+
+    test "returns :ok for empty list" do
+      assert LinkValidator.validate_links([]) == :ok
+    end
+
+    test "reports line numbers correctly" do
+      links = [
+        "/blog/engineering/ok",
+        "/blog/bad/slug",
+        "/blog/releases/ok"
+      ]
+
+      assert LinkValidator.validate_links(links) == {
+               :error,
+               [{2, "/blog/bad/slug", "unknown blog ID: bad"}]
+             }
+    end
+  end
+
+  describe "validate_body/2" do
+    test "returns :ok when body has no internal blog links" do
+      body = "<p>Just text, no links.</p>"
+
+      assert LinkValidator.validate_body(body, :engineering) == :ok
+    end
+
+    test "returns :ok when all links are valid" do
+      body = "<p>[link](/blog/engineering/post)</p>"
+
+      assert LinkValidator.validate_body(body, :engineering) == :ok
+    end
+
+    test "returns errors with post context" do
+      body = "<p>[link](/blog/unknown/post)</p>"
+
+      assert LinkValidator.validate_body(body, :engineering) == {
+               :error,
+               [
+                 {
+                   1,
+                   "/blog/unknown/post",
+                   "unknown blog ID: unknown",
+                   post_id: nil
+                 }
+               ]
+             }
+    end
+
+    test "includes post_id in error tuples when provided" do
+      body = "<p>[link](/blog/unknown/post)</p>"
+
+      assert LinkValidator.validate_body(body, :engineering, post_id: "test-post") == {
+               :error,
+               [
+                 {
+                   1,
+                   "/blog/unknown/post",
+                   "unknown blog ID: unknown",
+                   post_id: "test-post"
+                 }
+               ]
+             }
+    end
+  end
+end