mtest: rust: allow parsing doctest output

Doctests have a slightly different output compared to what "protocol: rust"
supports:

   running 2 tests
   test rust/qemu-api/libqemu_api.rlib.p/structured/lib.rs - QemuAllocator (line 49) ... ignored
   test rust/qemu-api/libqemu_api.rlib.p/structured/zeroable.rs - zeroable::Zeroable (line 9) ... ok

   test result: ok. 1 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out; finished in 0.11s

Add a little more parsing in order to parse this correctly.  I plan to
contribute an extension of the rust module to invoke doctests, for now
this allows running rustdoc --test with "protocol: rust" and get
information about the subtests:

   2/3 qemu:unit+rust / rust-qemu-api-doctests           RUNNING
   ...
   ▶ 2/3 test rust/qemu-api/libqemu_api.rlib.p/structured/lib.rs:QemuAllocator:49 SKIP
   ▶ 2/3 test rust/qemu-api/libqemu_api.rlib.p/structured/zeroable.rs:zeroable.Zeroable:9 OK
   2/3 qemu:unit+rust / rust-qemu-api-doctests           OK              1.20s   1 subtests passed

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

mesonbuild/mtest.py

@@ -81,6 +81,9 @@
 UNENCODABLE_XML_CHR_RANGES = [fr'{chr(low)}-{chr(high)}' for (low, high) in UNENCODABLE_XML_UNICHRS]
 UNENCODABLE_XML_CHRS_RE = re.compile('([' + ''.join(UNENCODABLE_XML_CHR_RANGES) + '])')
 
+RUST_TEST_RE = re.compile(r'^test (?!result)(.*) \.\.\. (.*)$')
+RUST_DOCTEST_RE = re.compile(r'^(.*?) - (.*?) \(line (\d+)\)')
+
 
 def is_windows() -> bool:
     platname = platform.system().lower()
@@ -1157,8 +1160,12 @@ def parse_res(n: int, name: str, result: str) -> TAPParser.Test:
 
         n = 1
         async for line in lines:
-            if line.startswith('test ') and not line.startswith('test result'):
-                _, name, _, result = line.rstrip().split(' ')
+            match = RUST_TEST_RE.match(line)
+            if match:
+                name, result = match.groups()
+                doctest = RUST_DOCTEST_RE.match(name)
+                if doctest:
+                    name = ':'.join(doctest.groups())
                 name = name.replace('::', '.')
                 t = parse_res(n, name, result)
                 self.results.append(t)