FreezableTests.swift

// Copyright 2019 The TensorFlow Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import XCTest

@testable import TensorFlow

final class FreezableTests: XCTestCase {
  func testFreezableParameters() {
    // A dense layer with freezable properties.
    struct FreezableDense: Layer {
      @_Freezable var weight: Tensor<Float>
      @_Freezable var bias: Tensor<Float>

      init(weight: Tensor<Float>, bias: Tensor<Float>) {
        // Require scalar weight and bias for simplicity.
        precondition(weight.isScalar)
        precondition(bias.isScalar)
        self.weight = weight
        self.bias = bias
      }

      @differentiable
      func callAsFunction(_ input: Tensor<Float>) -> Tensor<Float> {
        return input * weight + bias
      }
    }

    var dense = FreezableDense(weight: Tensor(2), bias: Tensor(3))
    let grad = FreezableDense.TangentVector(weight: Tensor(4), bias: Tensor(1))

    dense.move(along: grad)
    XCTAssertEqual(Tensor(6), dense.weight)
    XCTAssertEqual(Tensor(4), dense.bias)

    // Freeze `dense.weight`: its value cannot be updated.
    dense.$weight.freeze()
    dense.move(along: grad)
    XCTAssertEqual(Tensor(6), dense.weight)
    XCTAssertEqual(Tensor(5), dense.bias)

    // Unfreeze `dense.weight`: its value can be updated again.
    dense.$weight.unfreeze()
    dense.move(along: grad)
    XCTAssertEqual(Tensor(10), dense.weight)
    XCTAssertEqual(Tensor(6), dense.bias)
  }

  static var allTests = [
    ("testFreezableParameters", testFreezableParameters)
  ]
}