如何模拟 Mono.from(commandResult).block();

Question

I have a class that invokes mongodb using reactive library and am writing a unit test that includes this private method. How to mock Mono.from(commandResult).block() using mockito?

private Document runCommand(final String command) {
        final MongoDatabase db = mongoClient.getDatabase("admin");
        final Bson bsonDocument = Document.parse(command).toBsonDocument();
        final Publisher<Document> commandResult = db.runCommand(bsonDocument);
        return Mono.from(commandResult).block();
    }

Answer 1

Retuning Mono.just() worked

@Test
    void initializeDBTest() {
        final Document bsonDoc = Document.parse(isCSResponse);
        Mockito.when(mongoClient.getDatabase("admin")).thenReturn(db);
        Mockito.when(db.runCommand(Mockito.any())).thenReturn(Mono.just(bsonDoc));
        manageDB.initializeDB();
    }