[lldb] Add a test for capturing stdout/stderr from Python commands (llvm#168138)

Author: JDevlieghere

lldb/test/API/python_api/command_script_output/TestCommandScriptOutput.py

@@ -0,0 +1,47 @@
+"""
+Test that HandleCommand captures stdout and stderr from script commands.
+"""
+
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+
+
+class CommandScriptOutputTestCase(TestBase):
+    NO_DEBUG_INFO_TESTCASE = True
+
+    def test_script_command_stdout_stderr(self):
+        """Test that HandleCommand captures stdout and stderr from script commands."""
+        ci = self.dbg.GetCommandInterpreter()
+        self.assertTrue(ci, VALID_COMMAND_INTERPRETER)
+
+        res = lldb.SBCommandReturnObject()
+
+        # Execute a script command that writes to stdout.
+        ci.HandleCommand("script print('Hello stdout')", res)
+        self.assertTrue(res.Succeeded())
+        self.assertIn("Hello stdout", res.GetOutput())
+
+        # Execute a script command that writes to stderr.
+        ci.HandleCommand("script import sys; sys.stderr.write('Hello stderr\\n')", res)
+        self.assertTrue(res.Succeeded())
+        self.assertIn("Hello stderr", res.GetOutput())
+
+        # Execute a script command that writes to both stdout and stderr.
+        ci.HandleCommand(
+            "script import sys; print('Output line'); sys.stderr.write('Error line\\n')",
+            res,
+        )
+        self.assertTrue(res.Succeeded())
+        self.assertIn("Output line", res.GetOutput())
+        self.assertIn("Error line", res.GetOutput())
+
+        # Test that multiple print statements are captured.
+        ci.HandleCommand(
+            "script print('Line 1'); print('Line 2'); print('Line 3')", res
+        )
+        self.assertTrue(res.Succeeded())
+        output = res.GetOutput()
+        self.assertIn("Line 1", output)
+        self.assertIn("Line 2", output)
+        self.assertIn("Line 3", output)