mtest: rust: allow parsing doctest output

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

  running 2 tests
  test ../doctest1.rs - my_func (line 7) ... ignored
  test ../doctest1.rs - (line 3) ... ok

  test result: ok. 1 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out; finished in 0.12s

Add a little more parsing in order to accept this; a simple minded split()
fails to unpack the tuple.  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:

  ▶ 4/8 ../doctest1.rs:my_func:7                     SKIP
  ▶ 4/8 ../doctest1.rs:3                             OK
  4/8 rust_unit_tests:doctests / rust doctest        OK              0.28s   1 subtests passed

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

3 files changed, 36 insertions, 2 deletions

diff --git a/mesonbuild/mtest.py b/mesonbuild/mtest.py
index 503cb1432..27e0f796a 100644
--- a/mesonbuild/mtest.py
+++ b/mesonbuild/mtest.py
@@ -81,6 +81,9 @@ if sys.maxunicode >= 0x10000:
 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 +1160,14 @@ class TestRunRust(TestRun):
 
         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((x.rstrip() for x in doctest.groups() if x))
+                else:
+                    name = name.rstrip()
                 name = name.replace('::', '.')
                 t = parse_res(n, name, result)
                 self.results.append(t)
diff --git a/test cases/rust/9 unit tests/doctest1.rs b/test cases/rust/9 unit tests/doctest1.rs
new file mode 100644
index 000000000..d270f7d67
--- /dev/null
+++ b/test cases/rust/9 unit tests/doctest1.rs
@@ -0,0 +1,12 @@
+//! This is a doctest
+//!
+//! ```
+//! assert_eq!(2+2, 4)
+//! ```
+
+/// ```ignore
+/// this one will be skipped
+/// ```
+fn my_func()
+{
+}
diff --git a/test cases/rust/9 unit tests/meson.build b/test cases/rust/9 unit tests/meson.build
index e62745781..aa9da6796 100644
--- a/test cases/rust/9 unit tests/meson.build
+++ b/test cases/rust/9 unit tests/meson.build
@@ -31,6 +31,19 @@ test(
   suite : ['foo'],
 )
 
+rustdoc = find_program('rustdoc', required: false)
+if rustdoc.found()
+  # rustdoc is invoked mostly like rustc.  This is a simple example
+  # where it is easy enough to invoke it by hand.
+  test(
+    'rust doctest',
+    rustdoc,
+    args : ['--test', '--crate-name', 'doctest1', '--crate-type', 'lib', files('doctest1.rs')],
+    protocol : 'rust',
+    suite : ['doctests'],
+  )
+endif
+
 exe = executable('rust_exe', ['test2.rs', 'test.rs'], build_by_default : false)
 
 rust = import('rust')