feat: Add Angular, HTML, and SCSS / Sass language servers (#1439)

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Co-authored-by: Pavlo Basanets <Pavlo_Basanets@epam.com>

test/solidlsp/html_ls/test_html_basic.py

@@ -0,0 +1,54 @@
+"""
+Basic integration tests for the HTML language server.
+
+The HTML LSP (vscode-html-language-server) provides in-file document symbols
+based on the element tree. Cross-file navigation (definition / references) is
+not meaningful for HTML and is therefore not tested here.
+"""
+
+from pathlib import Path
+
+import pytest
+
+from solidlsp import SolidLanguageServer
+from solidlsp.ls_config import Language
+from test.solidlsp.conftest import request_all_symbols
+
+
+@pytest.mark.html
+class TestHtmlLanguageServerBasics:
+    """Smoke + symbol tests for the HTML language server."""
+
+    @pytest.mark.parametrize("language_server", [Language.HTML], indirect=True)
+    @pytest.mark.parametrize("repo_path", [Language.HTML], indirect=True)
+    def test_ls_is_running(self, language_server: SolidLanguageServer, repo_path: Path) -> None:
+        assert language_server.is_running()
+        assert Path(language_server.language_server.repository_root_path).resolve() == repo_path.resolve()
+
+    @pytest.mark.parametrize("language_server", [Language.HTML], indirect=True)
+    def test_index_document_symbols(self, language_server: SolidLanguageServer) -> None:
+        """The HTML LSP exposes elements/IDs as document symbols."""
+        all_symbols, _ = language_server.request_document_symbols("index.html").get_all_symbols_and_roots()
+        names = [s["name"] for s in all_symbols]
+
+        # vscode-html-language-server reports elements by tag name and emits an entry
+        # per element with an id attribute. Names contain the id like "header#page-header"
+        # or just the tag like "head" for elements without an id; we check both forms.
+        joined = " | ".join(names)
+        for expected_id in ("page-header", "site-title", "main-nav", "section-features", "feature-list", "page-footer"):
+            assert expected_id in joined, f"Expected id '{expected_id}' to appear in HTML symbols: {names}"
+
+    @pytest.mark.parametrize("language_server", [Language.HTML], indirect=True)
+    def test_about_document_symbols(self, language_server: SolidLanguageServer) -> None:
+        all_symbols, _ = language_server.request_document_symbols("about.html").get_all_symbols_and_roots()
+        names = [s["name"] for s in all_symbols]
+        joined = " | ".join(names)
+        for expected_id in ("page-header", "about-title", "main-nav", "about-article"):
+            assert expected_id in joined, f"Expected id '{expected_id}' to appear in HTML symbols: {names}"
+
+    @pytest.mark.parametrize("language_server", [Language.HTML], indirect=True)
+    def test_full_symbol_tree_includes_both_files(self, language_server: SolidLanguageServer) -> None:
+        all_symbols = request_all_symbols(language_server)
+        relative_paths = {s.get("location", {}).get("relativePath") for s in all_symbols}
+        assert "index.html" in relative_paths
+        assert "about.html" in relative_paths