add package line

Author: MrMaydo

src/header_generator.py

@@ -0,0 +1,8 @@
+import re
+
+
+def set_package(package: str) -> str:
+    PACKAGE_REGEX = r"^(?:[a-z_][a-z0-9_]*)(?:\.(?:[a-z_][a-z0-9_]*))*$"
+    if not re.match(PACKAGE_REGEX, package):
+        raise ValueError(f"Invalid package: '{package}'")
+    return f"package {package}"

tests/test_header_generator.py

@@ -0,0 +1,23 @@
+import pytest
+
+from src.header_generator import set_package
+
+
+def test_set_package():
+    example = "org.example.hyphenated_name"
+    expected = f"package {example}"
+    assert set_package(example) == expected
+
+    example_2 = "com.example._123name"
+    expected_2 = f"package {example_2}"
+    assert set_package(example_2) == expected_2
+
+
+def test_set_package_illegal_name():
+    example = "org.example.hyphenated-name"
+    with pytest.raises(ValueError):
+        set_package(example)
+
+    example_2 = "com.example.123name"
+    with pytest.raises(ValueError):
+        set_package(example_2)