tests/tcg: Factor out gdbstub test functions

Both the report() function as well as the initial gdbstub test sequence
are copy-pasted into ~10 files with slight modifications. This
indicates that they are indeed generic, so factor them out. While
at it, add a few newlines to make the formatting closer to PEP-8.

Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Message-Id: <20240129093410.3151-3-iii@linux.ibm.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

tests/guest-debug/test_gdbstub.py

@@ -0,0 +1,60 @@
+"""Helper functions for gdbstub testing
+
+"""
+from __future__ import print_function
+import gdb
+import os
+import sys
+import traceback
+
+fail_count = 0
+
+
+def report(cond, msg):
+    """Report success/fail of a test"""
+    if cond:
+        print("PASS: {}".format(msg))
+    else:
+        print("FAIL: {}".format(msg))
+        global fail_count
+        fail_count += 1
+
+
+def main(test, expected_arch=None):
+    """Run a test function
+
+    This runs as the script it sourced (via -x, via run-test.py)."""
+    try:
+        inferior = gdb.selected_inferior()
+        arch = inferior.architecture()
+        print("ATTACHED: {}".format(arch.name()))
+        if expected_arch is not None:
+            report(arch.name() == expected_arch,
+                   "connected to {}".format(expected_arch))
+    except (gdb.error, AttributeError):
+        print("SKIP: not connected")
+        exit(0)
+
+    if gdb.parse_and_eval("$pc") == 0:
+        print("SKIP: PC not set")
+        exit(0)
+
+    try:
+        test()
+    except:
+        print("GDB Exception:")
+        traceback.print_exc(file=sys.stdout)
+        global fail_count
+        fail_count += 1
+        if "QEMU_TEST_INTERACTIVE" in os.environ:
+            import code
+            code.InteractiveConsole(locals=globals()).interact()
+        raise
+
+    try:
+        gdb.execute("kill")
+    except gdb.error:
+        pass
+
+    print("All tests complete: {} failures".format(fail_count))
+    exit(fail_count)