Unit tests for service

ServiceTests.swift

import Testing
import Foundation
import SwiftData
@testable import ExampleApp

@Suite("Example Service Test") struct ExampleServiceTest {
  
  let someOtherModelDescriptor = FetchDescriptor<SomeOtherModel>(sortBy: [SortDescriptor(\SomeOtherModel.created, order: .reverse)])
  
  @MainActor @Test("Adding SomeModel record when have SomeOtherModel record") func addRecordWithExisting() throws {
    // setup
    let config = ModelConfiguration(isStoredInMemoryOnly: true)
    let container = try ModelContainer(for: SomeOtherModel.self, SomeModel.self, configurations: config)
    let service = ExampleService(modelContext: container.mainContext)
    
    // Create SomeOtherModel record
    let someOtherRecord = SomeOtherModel(name: "Foo")
    container.mainContext.insert(someOtherRecord)
    
    // Check no existing SomeModel records before calling function
    service.fetchData()
    #expect(service.someList.count == 0)
    
    // Call function and check it's set everything up correctly
    service.someComplexMultiModelAction()
    #expect(service.someList.count == 1)
    let otherModelRecords = try container.mainContext.fetch(someOtherModelDescriptor)
    #expect(otherModelRecords.count == 1)
    #expect(service.someList.first.otherModelInstance == otherModelRecords.first)
  }
  
  @MainActor @Test("Adding SomeModel record when no SomeOtherModel record") func addRecordNoExisting() throws {
    // setup
    let config = ModelConfiguration(isStoredInMemoryOnly: true)
    let container = try ModelContainer(for: SomeOtherModel.self, SomeModel.self, configurations: config)
    let service = ExampleService(modelContext: container.mainContext)
    
    // Check no existing SomeOtherModel records before calling function
    let otherModelRecordsBefore = try container.mainContext.fetch(someOtherModelDescriptor)
    #expect(otherModelRecordsBefore.count == 0)
    
    // Check no existing SomeModel records before calling function
    service.fetchData()
    #expect(service.someList.count == 0)
    
    // Call function and check it's set everything up correctly
    service.someComplexMultiModelAction()
    #expect(service.someList.count == 1)
    let otherModelRecordsAfter = try container.mainContext.fetch(someOtherModelDescriptor)
    #expect(otherModelRecordsAfter.count == 1)
    #expect(service.someList.first.otherModelInstance == otherModelRecordsAfter.first)
  }
}