improve suite of meson test (#3369)

docs/markdown/Reference-manual.md

@@ -1243,6 +1243,12 @@ Keyword arguments are the following:
 - `should_fail` when true the test is considered passed if the
   executable returns a non-zero return value (i.e. reports an error)
 
+- `suite` `'label'` (or list of labels `['label1', 'label2']`)
+  attached to this test. The suite name is qualified by a (sub)project
+  name resulting in `(sub)project_name:label`. In the case of a list
+  of strings, the suite names will be `(sub)project_name:label1`,
+  `(sub)project_name:label2`, etc.
+
 - `timeout` the amount of seconds the test is allowed to run, a test
   that exceeds its time limit is always considered failed, defaults to
   30 seconds

docs/markdown/Unit-tests.md

@@ -71,6 +71,14 @@ You can also run only a single test by giving its name:
 $ meson test testname
 ```
 
+Tests belonging to a suite `suite` can be run as follows
+
+```console
+$ meson test --suite (sub)project_name:suite
+```
+
+Since version *0.46*, `(sub)project_name` can be omitted if it is the top-level project.
+
 Sometimes you need to run the tests multiple times, which is done like this:
 
 ```console

mesonbuild/mtest.py

@@ -476,6 +476,25 @@ TIMEOUT: %4d
             (prj_match, st_match) = TestHarness.split_suite_string(suite)
             for prjst in test.suite:
                 (prj, st) = TestHarness.split_suite_string(prjst)
+
+                # the SUITE can be passed as
+                #     suite_name
+                # or
+                #     project_name:suite_name
+                # so we need to select only the test belonging to project_name
+
+                # this if hanlde the first case (i.e., SUITE == suite_name)
+
+                # in this way we can run tests belonging to different
+                # (sub)projects which share the same suite_name
+                if not st_match and st == prj_match:
+                    return True
+
+                # these two conditions are needed to handle the second option
+                # i.e., SUITE == project_name:suite_name
+
+                # in this way we select the only the tests of
+                # project_name with suite_name
                 if prj_match and prj != prj_match:
                     continue
                 if st_match and st != st_match: