tester: add unit tests iteration 2

tests/__init__.py

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

tests/test_hello.py

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+"""Unit tests for hello.py module."""
+
+import subprocess
+import unittest
+from pathlib import Path
+
+
+class TestHelloOutput(unittest.TestCase):
+    """Tests for hello.py output behavior."""
+
+    def setUp(self):
+        """Set up test fixtures."""
+        self.hello_script = Path(__file__).parent.parent / "hello.py"
+        self.working_dir = Path(__file__).parent.parent
+
+    def test_hello_prints_expected_message(self):
+        """Test that hello.py prints 'Hello, World!' to stdout."""
+        result = subprocess.run(
+            ["python3", str(self.hello_script)],
+            capture_output=True,
+            text=True,
+            cwd=self.working_dir
+        )
+        self.assertIn("Hello, World!", result.stdout)
+
+    def test_hello_exact_output(self):
+        """Test that hello.py output matches exactly (with newline)."""
+        result = subprocess.run(
+            ["python3", str(self.hello_script)],
+            capture_output=True,
+            text=True,
+            cwd=self.working_dir
+        )
+        self.assertEqual(result.stdout.strip(), "Hello, World!")
+
+    def test_hello_exit_code_zero(self):
+        """Test that hello.py exits with code 0."""
+        result = subprocess.run(
+            ["python3", str(self.hello_script)],
+            capture_output=True,
+            text=True,
+            cwd=self.working_dir
+        )
+        self.assertEqual(result.returncode, 0)
+
+    def test_hello_no_stderr(self):
+        """Test that hello.py produces no stderr output."""
+        result = subprocess.run(
+            ["python3", str(self.hello_script)],
+            capture_output=True,
+            text=True,
+            cwd=self.working_dir
+        )
+        self.assertEqual(result.stderr, "")
+
+    def test_hello_stdout_not_empty(self):
+        """Test that hello.py produces non-empty stdout."""
+        result = subprocess.run(
+            ["python3", str(self.hello_script)],
+            capture_output=True,
+            text=True,
+            cwd=self.working_dir
+        )
+        self.assertTrue(len(result.stdout) > 0)
+
+
+class TestHelloFileExists(unittest.TestCase):
+    """Tests for hello.py file existence and content."""
+
+    def setUp(self):
+        """Set up test fixtures."""
+        self.hello_script = Path(__file__).parent.parent / "hello.py"
+
+    def test_hello_file_exists(self):
+        """Test that hello.py file exists."""
+        self.assertTrue(self.hello_script.exists())
+
+    def test_hello_file_is_python(self):
+        """Test that hello.py has .py extension."""
+        self.assertEqual(self.hello_script.suffix, ".py")
+
+    def test_hello_file_contains_print(self):
+        """Test that hello.py contains a print statement."""
+        content = self.hello_script.read_text()
+        self.assertIn("print", content)
+
+    def test_hello_file_contains_hello_world(self):
+        """Test that hello.py contains 'Hello, World!' string."""
+        content = self.hello_script.read_text()
+        self.assertIn("Hello, World!", content)
+
+
+if __name__ == "__main__":
+    unittest.main()