fix: add smoke tests for CI (23 tests for core modules)

- Import smoke tests for all 11 core modules
- Unit tests for utils (ensure_unique_path, validate_pdf, human_readable_size)
- Unit tests for split (parse_page_ranges, SplitMode)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: LostSunset

tests/test_core/test_imports.py

@@ -0,0 +1,25 @@
+"""Smoke tests: verify all modules can be imported."""
+
+import importlib
+
+import pytest
+
+CORE_MODULES = [
+    "pdf_toolbox",
+    "pdf_toolbox.core.utils",
+    "pdf_toolbox.core.unlock",
+    "pdf_toolbox.core.convert",
+    "pdf_toolbox.core.protect",
+    "pdf_toolbox.core.merge",
+    "pdf_toolbox.core.split",
+    "pdf_toolbox.core.rotate",
+    "pdf_toolbox.core.watermark",
+    "pdf_toolbox.core.compress",
+    "pdf_toolbox.core.reorder",
+]
+
+
+@pytest.mark.parametrize("module_name", CORE_MODULES)
+def test_import_core_module(module_name: str) -> None:
+    mod = importlib.import_module(module_name)
+    assert mod is not None

tests/test_core/test_split.py

@@ -0,0 +1,27 @@
+"""Tests for core split module."""
+
+from pdf_toolbox.core.split import SplitMode, parse_page_ranges
+
+
+class TestParsePageRanges:
+    def test_single_page(self) -> None:
+        result = parse_page_ranges("3", total_pages=10)
+        assert result == [(2, 2)]
+
+    def test_range(self) -> None:
+        result = parse_page_ranges("1-3", total_pages=10)
+        assert result == [(0, 2)]
+
+    def test_multiple_ranges(self) -> None:
+        result = parse_page_ranges("1-3, 5, 7-9", total_pages=10)
+        assert len(result) == 3
+        assert result[0] == (0, 2)
+        assert result[1] == (4, 4)
+        assert result[2] == (6, 8)
+
+
+class TestSplitMode:
+    def test_modes_exist(self) -> None:
+        assert SplitMode.BY_RANGE is not None
+        assert SplitMode.EVERY_N_PAGES is not None
+        assert SplitMode.EXTRACT_PAGES is not None

tests/test_core/test_utils.py

@@ -0,0 +1,49 @@
+"""Tests for core utility functions."""
+
+from pathlib import Path
+
+from pdf_toolbox.core.utils import ensure_unique_path, human_readable_size, validate_pdf
+
+
+class TestEnsureUniquePath:
+    def test_unique_path_no_conflict(self, tmp_path: Path) -> None:
+        target = tmp_path / "output.pdf"
+        result = ensure_unique_path(target)
+        assert result == target
+
+    def test_unique_path_with_conflict(self, tmp_path: Path) -> None:
+        target = tmp_path / "output.pdf"
+        target.touch()
+        result = ensure_unique_path(target)
+        assert result != target
+        assert result.stem.startswith("output")
+        assert result.suffix == ".pdf"
+
+
+class TestValidatePdf:
+    def test_valid_pdf(self, tmp_path: Path) -> None:
+        pdf = tmp_path / "test.pdf"
+        pdf.write_bytes(b"%PDF-1.4 fake content")
+        assert validate_pdf(pdf) is True
+
+    def test_invalid_extension(self, tmp_path: Path) -> None:
+        txt = tmp_path / "test.txt"
+        txt.write_text("not a pdf")
+        assert validate_pdf(txt) is False
+
+    def test_nonexistent_file(self, tmp_path: Path) -> None:
+        assert validate_pdf(tmp_path / "missing.pdf") is False
+
+
+class TestHumanReadableSize:
+    def test_bytes(self) -> None:
+        result = human_readable_size(500)
+        assert "500" in result and "B" in result
+
+    def test_kilobytes(self) -> None:
+        result = human_readable_size(1536)
+        assert "KB" in result
+
+    def test_megabytes(self) -> None:
+        result = human_readable_size(2 * 1024 * 1024)
+        assert "MB" in result