ci/lava: Fix lava-tags parsing

python-fire auto-converts `item1,item2` into a tuple, but if there is a
dash `-` inside the argument, it treats it as a string.

Let's validate the data, when it comes as a `str` or `tuple`.

For more details, here are the tested scenarios:

| --lava-tags= | Type  | Value               |
|--------------|-------|---------------------|
| None         | bool  | True                |
| ''           | str   | ''                  |
| tag1         | str   | "tag1"              |
| tag1,        | tuple | ("tag1",)           |
| tag-1,tag-2  | str   | 'tag-1,tag-2'       |
| tag1,tag2    | tuple | ("tag1", "tag2")    |
| ','          | str   | ','                 |
| ',,'         | str   | ',,'                |
| 'tag1,,'     | str   | 'tag1,,'            |

See also:
https://google.github.io/python-fire/guide/#argument-parsing

Signed-off-by: Guilherme Gallo <guilherme.gallo@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31882>

.gitlab-ci/lava/lava_job_submitter.py

@@ -407,7 +407,7 @@ class LAVAJobSubmitter(PathResolver):
     kernel_image_type: str = ""
     kernel_url_prefix: str = None
     kernel_external: str = None
-    lava_tags: str = ""  # Comma-separated LAVA tags for the job
+    lava_tags: str | tuple[str, ...] = ()  # Comma-separated LAVA tags for the job
     mesa_job_name: str = "mesa_ci_job"
     pipeline_info: str = ""
     rootfs_url: str = None

.gitlab-ci/lava/utils/lava_job_definition.py

@@ -121,6 +121,22 @@ class LAVAJobDefinition:
         yaml.dump(self.generate_lava_yaml_payload(), job_stream)
         return job_stream.getvalue()
 
+    def consume_lava_tags_args(self, values: dict[str, Any]):
+        # python-fire parses --lava-tags without arguments as True
+        if isinstance(self.job_submitter.lava_tags, tuple):
+            values["tags"] = self.job_submitter.lava_tags
+        # python-fire parses "tag-1,tag2" as str and "tag1,tag2" as tuple
+        # even if the -- --separator is something other than '-'
+        elif isinstance(self.job_submitter.lava_tags, str):
+            # Split string tags by comma, removing any trailing commas
+            values["tags"] = self.job_submitter.lava_tags.rstrip(",").split(",")
+        # Ensure tags are always a list of non-empty strings
+        if "tags" in values:
+            values["tags"] = [tag for tag in values["tags"] if tag]
+        # Remove empty tags
+        if "tags" in values and not values["tags"]:
+            del values["tags"]
+
     def generate_metadata(self) -> dict[str, Any]:
         # General metadata and permissions
         values = {
@@ -150,8 +166,7 @@ class LAVAJobDefinition:
             },
         }
 
-        if self.job_submitter.lava_tags:
-            values["tags"] = self.job_submitter.lava_tags.split(",")
+        self.consume_lava_tags_args(values)
 
         # QEMU lava jobs mandate proper arch value in the context
         if self.job_submitter.boot_method == "qemu-nfs":