tests/testthat/test-solution-milp.R

In dirkschumacher/romp: Model and Solve Mixed Integer Linear Programs

context("MILP: solution")

test_that("export single var to numeric", {
  model <- MILPModel() %>%
    add_variable(x, ub = 1) %>%
    add_variable(y, ub = 1) %>%
    add_constraint(x + y <= 1) %>%
    set_objective(x + y)
  solution <- new_solution(
    status = "optimal",
    model = model,
    objective_value = 2,
    solution = setNames(c(1, 1), c("x", "y"))
  )
  result <- get_solution(solution, x)
  expect_equivalent(result, 1)
})

test_that("export solutions to data.frame if var is indexed", {
  model <- MILPModel() %>%
    add_variable(x[i], i = 1:3, ub = 1) %>%
    set_objective(sum_expr(x[i], i = 1:3))
  solution <- new_solution(
    status = "optimal",
    model = model,
    objective_value = 3,
    solution = setNames(
      c(1, 1, 1),
      c("x[1]", "x[3]", "x[3]")
    )
  )
  expect_error(get_solution(solution, x))
})

test_that("export solutions to data.frame with index", {
  model <- MILPModel() %>%
    add_variable(x[i], i = 1:3, ub = 1) %>%
    set_objective(sum_expr(x[i], i = 1:3))
  solution <- new_solution(
    status = "optimal",
    model = model,
    objective_value = 3,
    solution = setNames(c(1, 1, 1), c("x[1]", "x[2]", "x[3]"))
  )
  result <- get_solution(solution, x[i])
  expect_s3_class(result, "data.frame")
  expect_equivalent(as.numeric(result$i), c(1, 2, 3))
})

test_that("export infeasible solutions to data.frame", {
  model <- MILPModel() %>%
    add_variable(x[i], i = 1:3, ub = 1) %>%
    set_objective(sum_expr(x[i], i = 1:3))
  solution <- new_solution(
    status = "infeasible",
    model = model,
    objective_value = 3,
    solution = setNames(c(1, 1, 1), c("x[1]", "x[3]", "x[3]"))
  )
  result <- get_solution(solution, x[i])
  expect_s3_class(result, "data.frame")
  expect_equal(nrow(result), 3)
})


test_that("export solutions to single value if all indexes bound", {
  model <- MILPModel() %>%
    add_variable(x[i], i = 1:3, ub = 1) %>%
    add_variable(y[i], i = 1:3, ub = 1) %>%
    set_objective(sum_expr(x[i], i = 1:3))
  solution <- new_solution(
    status = "optimal",
    model = model,
    objective_value = 3,
    solution = setNames(
      c(2, 2, 2, 1, 1, 1),
      c(
        "y[1]", "y[3]", "y[3]",
        "x[1]", "x[3]", "x[3]"
      )
    )
  )
  result <- get_solution(solution, y[1])
  expect_equivalent(result, 2)
})

test_that("export solutions to df in a model with more than one variable", {
  model <- MILPModel() %>%
    add_variable(x[i], i = 1:3, ub = 1) %>%
    add_variable(y[i], i = 1:3, ub = 1) %>%
    set_objective(sum_expr(x[i], i = 1:3))
  solution <- new_solution(
    status = "optimal",
    model = model,
    objective_value = 3,
    solution = setNames(
      c(2, 2, 2, 1, 1, 1),
      c(
        "y[1]", "y[3]", "y[3]",
        "x[1]", "x[3]", "x[3]"
      )
    )
  )
  result <- get_solution(solution, y[i])
  expect_equivalent(result$value, c(2, 2, 2))
})

test_that("solution has a nice default output", {
  model <- MILPModel() %>%
    add_variable(x[i], i = 1:3, ub = 1) %>%
    add_variable(y[i], i = 1:3, ub = 1) %>%
    set_objective(sum_expr(x[i], i = 1:3))
  solution <- new_solution(
    status = "optimal",
    model = model,
    objective_value = 3,
    solution = setNames(
      c(2, 2, 2, 1, 1, 1),
      c(
        "y[1]", "y[3]", "y[3]",
        "x[1]", "x[3]", "x[3]"
      )
    )
  )
  expect_output(show(solution), "Status: optimal\n")
  expect_output(show(solution), "Objective value: 3")
})

test_that("solution indexes should not be factors", {
  model <- MILPModel() %>%
    add_variable(x[i], i = 1:3, ub = 1) %>%
    add_variable(y[i], i = 1:3, ub = 1) %>%
    set_objective(sum_expr(x[i], i = 1:3))
  solution <- new_solution(
    status = "optimal",
    model = model,
    objective_value = 3,
    solution = setNames(
      c(2, 2, 2, 1, 1, 1),
      c(
        "y[1]", "y[2]", "y[3]",
        "x[1]", "x[2]", "x[3]"
      )
    )
  )
  expect_equal(class(get_solution(solution, y[i])$i), "integer")
})

test_that("objective_value gets the obj. value", {
  model <- MILPModel() %>%
    add_variable(x[i, j], i = 10:11, j = 10:12, ub = 1) %>%
    set_objective(sum_expr(x[10, i], i = 10:12))
  solution <- new_solution(
    status = "optimal",
    model = model,
    objective_value = 3,
    solution = setNames(
      c(2, 2, 2, 1, 1, 1),
      c(
        "x[10,10]", "x[10,11]", "x[10,12]",
        "x[11,10]", "x[11,11]", "x[11,12]"
      )
    )
  )
  expect_equal(3, objective_value(solution))
})

test_that("solver_status gets the solver_status", {
  model <- MILPModel() %>%
    add_variable(x[i, j], i = 10:11, j = 10:12, ub = 1) %>%
    set_objective(sum_expr(x[10, i], i = 10:12))
  solution <- new_solution(
    status = "optimal",
    model = model,
    objective_value = 3,
    solution = setNames(
      c(2, 2, 2, 1, 1, 1),
      c(
        "x[10,10]", "x[10,11]", "x[10,12]",
        "x[11,10]", "x[11,11]", "x[11,12]"
      )
    )
  )
  expect_equal("optimal", solver_status(solution))
})