[lldb] Add test for unavailable registers

[DavidSpickett]

Summary

Prior to this the only check was that we did not print
this message when reading registers that should exist.

I thought there was an indentation bug here so I wrote a test
for it. There is not, but we could do with the coverage anyway.

[DavidSpickett]

lldb/test/API/commands/register/register/TestRegistersUnavailable.py

57

The only difference here if you have the x86 backend vs. not, is that there is another set after these two. I've checked the test in both configurations and it passes.

[DavidSpickett]

ping!

[rupprecht]

Seems like most xml-based tests like this are in lldb/test/API/functionalities/gdb_remote_client, is there a reason this is not in that package too?

[DavidSpickett]

It's not in that dir because it's testing how the register command handles missing registers, rather than how the gdb client does. It assumes that the gdb client is correctly doing its job.

And it seemed like the place one would look if you wondered whether there was an existing test.

[DavidSpickett]

The non XML way to do this is just reading bogus register names (and is already tested). However that's all or nothing so it doesn't prove that when there is a mix of available and unavailable registers the command works correctly.

[DavidSpickett]

On second thought I think you can do this without XML, I'll figure that out.

[DavidSpickett]

Remove the need for regex, with the tradeoff that you need
the X86 backend which is pretty common to have.

[rupprecht]

lldb/test/API/commands/register/register/TestRegistersUnavailable.py

44–54

optional: IIUC, patterns takes a list of patterns which are checked in order, so you could remove extraneous regexes like this one and pass a list instead.

[DavidSpickett]

lldb/test/API/commands/register/register/TestRegistersUnavailable.py

44–54

That is how substrs work but regex is applied to the full output each time: https://github.com/llvm/llvm-project/blob/56d94a90dbbf1845ec71cd749691c74c1dd8a3ef/lldb/packages/Python/lldbsuite/test/lldbtest.py#L2382

So I will keep this as it is.

lldb/test/API/commands/register/register/TestRegistersUnavailable.py

+""" Check that unavailable registers are reported when reading register sets."""
+
+from textwrap import dedent
+import lldb
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+from lldbsuite.test.gdbclientutils import *
+from lldbsuite.test.lldbgdbclient import GDBRemoteTestBase
+
+class MyResponder(MockGDBServerResponder):
+    def readRegisters(self):
+        return "E01"
+
+    def readRegister(self, regnum):
+        # Only allow reads of rip.
+        if regnum in [0, 1, 2]:
+            return "E01"
+        return "5555555555555555"
+
+    def qXferRead(self, obj, annex, offset, length):
+        if annex == "target.xml":
+            return """<?xml version="1.0"?>
+                <target version="1.0">
+                  <architecture>i386:x86-64</architecture>
+                  <feature name="org.gnu.gdb.i386.core">
+                    <reg name="rax" bitsize="64" regnum="0" group="general"/>
+                    <reg name="rbx" bitsize="64" regnum="1" group="general"/>
+                    <reg name="rsi" bitsize="64" regnum="2" group="other"/>
+                    <reg name="rip" bitsize="64" regnum="3" group="general" generic="pc"/>
+                  </feature>
+                </target>""", False
+        else:
+            return None, False
+
+class TestRegistersUnavailable(GDBRemoteTestBase):
+    @skipIfXmlSupportMissing
+    @skipIfRemote
+    def test_unavailable_registers(self):
+        self.server.responder = MyResponder()
+        target = self.dbg.CreateTarget('')
+
+        if self.TraceOn():
+            self.runCmd("log enable gdb-remote packets process")
+            self.addTearDownHook(
+                lambda: self.runCmd("log disable gdb-remote packets process"))
+
+        process = self.connect(target)
+        lldbutil.expect_state_changes(self, self.dbg.GetListener(), process,
+                                      [lldb.eStateStopped])
+
+        self.expect("register read --all", substrs=[
+            "general:\n"
+            "       rip = 0x5555555555555555\n"
+            "2 registers were unavailable.\n"
+            "\n"
+            "other:\n"
+            "1 registers were unavailable."])