Error: "discriminator: mapping is not supported"

[Danphillipz]

Issue

The following release seems to have introduced this error: #321

Since the upgrade to version 1.6.0 I have been seeing the following error message when trying to process my OAS with discriminator mappings.

{
  "error": {
    "message": "discriminator: mapping is not supported"
  }
}

Attached is a sample file which triggers the above error during processing:
discriminator-mapping-error-example.yaml

Research

From testing I can see that this removal seems to have triggered the issue as we are no longer deleting disciminator.mapping on subschemas.

Before, collectReferences was being called on the subschema which was tidying up discriminators on the subschema too. Now with that cleanup logic moved out of collectReferences and into cleanupDiscriminators it is no longer being applied at the subschema level, only on the main schema object

I believe this should fix the error in the src/transform/minimumSchema.ts file:

const minimumSchema = (originalSchema, oas) => {
    const refToAdd = [];
    const refAdded = [];
    const collectReferences = (s) => {
        if (s.$ref && !refToAdd.includes(s.$ref) && !refAdded.includes(s.$ref)) {
            refToAdd.push(s.$ref);
        }
    };
    const handleNullableSchema = (s) => {
        if (s.$ref) {
            if (s.nullable && !s.type) {
                s.type = dereferenceOas(s, oas).type;
            }
            return;
        }
        if (s.nullable && !s.type) {
            s.type = "object";
        }
        if (s.nullable && !Array.isArray(s.type)) {
            s.type = [s.type, "null"];
        }
    };
    const schema = cloneDeep(originalSchema);
    delete schema.description;
    delete schema.example;
    traverse(schema, cleanupDiscriminators);
    traverse(schema, collectReferences);
    traverse(schema, handleNullableSchema);
    traverse(schema, convertExclusiveMinMax);
    while (refToAdd.length) {
        const ref = refToAdd.shift();
        const path = splitPath(ref);
        refAdded.push(ref);
        const subschema = cloneDeep(get$1(oas, path, {}));
        delete subschema.description;
        delete subschema.example;
        traverse(subschema, cleanupDiscriminators);  <<------- Adding this line to cleanup discriminators on subschemas
        traverse(subschema, collectReferences);
        traverse(subschema, handleNullableSchema);
        traverse(subschema, convertExclusiveMinMax);
        set(schema, path, subschema);
    }
    return schema;
};

[github-actions]

👋 Hi! The 'smartbear-supported' label has just been added to this issue, which will create an internal tracking ticket in PactFlow's Jira (PACT-4565). We will use this to prioritise and assign a team member to this task. All activity will be public on this ticket. For now, sit tight and we'll update this ticket once we have more information on the next steps.

See our documentation for more information.

[Danphillipz]

Unfortunately, the #343 release did not fix the issue.

while (refToAdd.length) {
        const ref = refToAdd.shift();
        const path = splitPath(ref);
        refAdded.push(ref);
        const subschema = cloneDeep(get$1(oas, path, {}));
        delete subschema.description;
        delete subschema.example;
        traverse(schema, cleanupDiscriminators); <-- incorrectly called on schema as opposed to subschema
        traverse(subschema, collectReferences);
        traverse(subschema, handleNullableSchema);
        traverse(subschema, convertExclusiveMinMax);
        set(schema, path, subschema);
    }

If possible, it may be worth adding some additional testing around this scenario. Given the current testing did not catch the regression introduced by #321 or that the fix in #343 didn't successfully resolve the issue.