Filter noisy oneOf schema warnings during tmt lint

tests/lint/plan/data/missing_required.fmf

@@ -1,4 +1,4 @@
 execute:
     how: tmt
 report:
-    how: polarion
+    how: reportportal

tests/lint/plan/test.sh

@@ -69,7 +69,20 @@ rlJournalStart
         rlAssertGrep "fail P001 unknown key \"summaryABCDEF\" is used" $rlRun_LOG
 
         rlRun -s "$tmt plan lint invalid-plugin-key" 0
-        rlAssertGrep 'warn C000 key "wrong" not recognized by schema$' $rlRun_LOG
+
+        # Make sure the noise is not there.
+        rlAssertNotGrep 'warn C000 key "wrong" not recognized by schema$' $rlRun_LOG
+        rlAssertNotGrep 'warn C000 value of "how" is not "ansible"' $rlRun_LOG
+        rlAssertNotGrep 'warn C000 key "wrong" not recognized by schema /schemas/prepare/errata' $rlRun_LOG
+        rlAssertNotGrep 'warn C000 value of "how" is not "errata"' $rlRun_LOG
+        rlAssertNotGrep 'warn C000 key "wrong" not recognized by schema /schemas/prepare/install' $rlRun_LOG
+        rlAssertNotGrep 'warn C000 value of "how" is not "install"' $rlRun_LOG
+        rlAssertNotGrep 'warn C000 value of "how" is not "shell"' $rlRun_LOG
+        rlAssertNotGrep 'warn C000 key "name" not recognized by schema /schemas/prepare/artifact' $rlRun_LOG
+        rlAssertNotGrep 'warn C000 key "wrong" not recognized by schema /schemas/prepare/artifact' $rlRun_LOG
+        rlAssertNotGrep 'warn C000 value of "how" is not "artifact"' $rlRun_LOG
+
+        # this is the relevant warning
         rlAssertGrep 'warn C000 key "wrong" not recognized by schema /schemas/prepare/feature' $rlRun_LOG
 
         rlRun -s "$tmt plan lint empty_env_file" 1
@@ -97,8 +110,17 @@ rlJournalStart
 
     rlPhaseStartTest "Lint of missing required property"
         rlRun -s "$tmt plan lint missing_required" 0
-        rlAssertGrep "warn C000 \"project-id\" is a required property by schema /schemas/report/polarion" "$rlRun_LOG"
-        rlAssertGrep "warn C000 fmf node failed schema validation" "$rlRun_LOG"
+
+        # Make sure the noise is not there.
+        rlAssertNotGrep "warn C000 value of \"how\" is not \"display\"" $rlRun_LOG
+        rlAssertNotGrep "warn C000 value of \"how\" is not \"html\"" $rlRun_LOG
+        rlAssertNotGrep "warn C000 value of \"how\" is not \"junit\"" $rlRun_LOG
+        rlAssertNotGrep "warn C000 value of \"how\" is not \"polarion\"" $rlRun_LOG
+        rlAssertNotGrep "warn C000 \"project-id\" is a required property by schema /schemas/report/polarion" $rlRun_LOG
+
+        # Make sure the relevant warning is there.
+        rlAssertGrep "warn C000 \"project\" is a required property by schema /schemas/report/reportportal" $rlRun_LOG
+        rlAssertGrep "warn C000 fmf node failed schema validation" $rlRun_LOG
     rlPhaseEnd
 
     rlPhaseStartTest "Lint of duplicate ids"

tmt/base/core.py

@@ -1158,7 +1158,32 @@ def detect_errors(error: jsonschema.ValidationError) -> LinterReturn:
                 # Validation errors can have "context", a list of "sub" errors encountered during
                 # validation. Interesting ones are identified & added to our error message.
                 if error.context:
-                    for suberror in error.context:
+                    # For oneOf validation (e.g., report step with multiple plugin schemas),
+                    # we only want to show errors from the schema that matches the 'how' value.
+                    relevant_suberrors: list[jsonschema.ValidationError] = []
+                    if (
+                        isinstance(error.validator, str)
+                        and error.validator == 'oneOf'
+                        and isinstance(instance := error.instance, dict)
+                        and 'how' in instance
+                    ):
+                        how_value = instance['how']
+                        # Look for errors that have a schema $id containing the how value.
+                        relevant_suberrors = [
+                            suberror
+                            for suberror in error.context
+                            if (
+                                isinstance(sub_schema := suberror.schema, dict)
+                                and '$id' in sub_schema
+                                and sub_schema['$id'].endswith(f'/{how_value}')
+                            )
+                        ]
+
+                    # No specific suberrors were identified, show them all.
+                    if not relevant_suberrors:
+                        relevant_suberrors = list(error.context)
+
+                    for suberror in relevant_suberrors:
                         yield from detect_errors(suberror)
 
             yield LinterOutcome.WARN, 'fmf node failed schema validation'