agent: Write a simple python hello world Iteration 3

.gitignore

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+# Python bytecode
+__pycache__/
+*.pyc
+
+# Pytest
+.pytest_cache/
+
+# Distribution / packaging
+dist/
+build/
+*.egg-info/

hello.py

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+print("Hello, World!")

tests/__init__.py

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+"""Tests package for hello.py."""

tests/test_hello.py

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+"""Tests for hello.py module using pytest."""
+
+import subprocess
+from pathlib import Path
+
+# Module-level constants to avoid duplication across test functions
+HELLO_SCRIPT = Path(__file__).parent.parent / "hello.py"
+WORKING_DIR = Path(__file__).parent.parent
+
+
+def run_hello():
+    """Run hello.py and return the subprocess result."""
+    return subprocess.run(
+        ["python3", str(HELLO_SCRIPT)],
+        capture_output=True,
+        text=True,
+        cwd=WORKING_DIR,
+    )
+
+
+class TestHelloOutput:
+    """Tests for hello.py output behavior."""
+
+    def test_hello_prints_expected_message(self):
+        """Test that hello.py prints 'Hello, World!' to stdout."""
+        result = run_hello()
+        assert "Hello, World!" in result.stdout
+
+    def test_hello_exact_output(self):
+        """Test that hello.py output matches exactly (with newline)."""
+        result = run_hello()
+        assert result.stdout.strip() == "Hello, World!"
+
+    def test_hello_exit_code_zero(self):
+        """Test that hello.py exits with code 0."""
+        result = run_hello()
+        assert result.returncode == 0
+
+    def test_hello_no_stderr(self):
+        """Test that hello.py produces no stderr output."""
+        result = run_hello()
+        assert result.stderr == ""
+
+    def test_hello_stdout_not_empty(self):
+        """Test that hello.py produces non-empty stdout."""
+        result = run_hello()
+        assert len(result.stdout) > 0
+
+
+class TestHelloFile:
+    """Tests for hello.py file existence and content."""
+
+    def test_hello_file_exists(self):
+        """Test that hello.py file exists."""
+        assert HELLO_SCRIPT.exists()
+
+    def test_hello_file_is_python(self):
+        """Test that hello.py has .py extension."""
+        assert HELLO_SCRIPT.suffix == ".py"
+
+    def test_hello_file_contains_print(self):
+        """Test that hello.py contains a print statement."""
+        content = HELLO_SCRIPT.read_text()
+        assert "print" in content
+
+    def test_hello_file_contains_hello_world(self):
+        """Test that hello.py contains 'Hello, World!' string."""
+        content = HELLO_SCRIPT.read_text()
+        assert "Hello, World!" in content