markbaseengine/Tests/01_Model/LongContext12BTest.swift

import XCTest
@testable import MarkBase

final class LongContext12BTest: XCTestCase {

    var engine: MarkBaseEngine!
    var model: E4BModel!
    let modelDir = "/Users/accusys/MarkBaseEngine/models/gemma-4-12b-it-4bit"
    let maxCtx = 2048

    override func setUp() {
        super.setUp()
        guard FileManager.default.fileExists(atPath: modelDir + "/model.safetensors.index.json") else {
            return
        }
        engine = try? MarkBaseEngine(autoCompile: true)
        model = try? E4BModel(modelDir: modelDir, engine: engine, maxContextLength: maxCtx)
    }

    func testLongContext256Tokens() throws {
        try XCTSkipIf(model == nil, "12B model not found")

        let promptLength = 256
        var tokens = [Int]()
        for i in 0..<promptLength {
            tokens.append(100 + (i % 1000))
        }

        for (pos, tokenId) in tokens.enumerated() {
            let logits = try model.forward(tokenId: tokenId, position: pos)
            if pos == 0 || pos == promptLength - 1 {
                let nanCount = logits.filter { $0.isNaN }.count
                XCTAssertEqual(nanCount, 0, "NaN at pos=\(pos)")
            }
            if pos % 64 == 0 {
                let sample = logits.prefix(5)
                let nanCount = logits.filter { $0.isNaN }.count
                print("  pos=\(pos): logits[0..5]=\(sample) NaN=\(nanCount)")
            }
        }

        var genTokens = tokens
        for i in 0..<5 {
            let logits = try model.forward(tokenId: genTokens.last ?? 0, position: genTokens.count - 1)
            let nanCount = logits.filter { $0.isNaN }.count
            XCTAssertEqual(nanCount, 0, "NaN at gen step \(i)")
            var maxIdx = 0
            var maxVal = logits[0]
            for j in 1..<logits.count {
                if logits[j] > maxVal { maxVal = logits[j]; maxIdx = j }
            }
            genTokens.append(maxIdx)
            print("  gen[\(i)]: token=\(maxIdx) logit=\(maxVal)")
        }
    }

    func testLongContext1024Tokens() throws {
        try XCTSkipIf(model == nil, "12B model not found")

        let promptLength = 1024
        var tokens = [Int]()
        for i in 0..<promptLength {
            tokens.append(100 + (i % 1000))
        }

        for (pos, tokenId) in tokens.enumerated() {
            let logits = try model.forward(tokenId: tokenId, position: pos)
            if pos == 0 || pos == promptLength - 1 || pos % 128 == 0 {
                let nanCount = logits.filter { $0.isNaN }.count
                XCTAssertEqual(nanCount, 0, "NaN at pos=\(pos)")
                print("  pos=\(pos): logits[0..3]=\(logits.prefix(3)) NaN=\(nanCount)")
            }
        }

        var genTokens = tokens
        for i in 0..<5 {
            let logits = try model.forward(tokenId: genTokens.last ?? 0, position: genTokens.count - 1)
            let nanCount = logits.filter { $0.isNaN }.count
            XCTAssertEqual(nanCount, 0, "NaN at gen step \(i)")
            var maxIdx = 0
            var maxVal = logits[0]
            for j in 1..<logits.count {
                if logits[j] > maxVal { maxVal = logits[j]; maxIdx = j }
            }
            genTokens.append(maxIdx)
            print("  gen[\(i)]: token=\(maxIdx) logit=\(maxVal)")
        }
    }
}