test_that("Function returns correct values", {
  
  # starting values
  
  A <- FuzzyNumbers::FuzzyNumber(-5, 3, 6, 20, left=function(x)
    pbeta(x,0.4,3),
    right=function(x) 1-x^(1/4),
    lower=function(alpha) qbeta(alpha,0.4,3),
    upper=function(alpha) (1-alpha)^4)
  
  B <- FuzzyNumbers::TrapezoidalFuzzyNumber(1,1.5,6,8)
  
  C <- FuzzyNumbers::TrapezoidalFuzzyNumber(-1,2,2,7)
  
  D <- FuzzyNumbers::PiecewiseLinearFuzzyNumber(1, 2, 3, 4,
                                                knot.n=1, knot.alpha=0.25, knot.left=1.5, knot.right=3.25)
  
  # snapshots tests
  
  
  expect_snapshot(
    
    {FuzzyApproximation(A)}
  )
  
  expect_snapshot(
    
    {FuzzyApproximation(B,method = "Naive")}
  )
  
  expect_snapshot(
    
    {FuzzyApproximation(C,method="ExpectedIntervalPreserving")}
  )
  
  expect_snapshot(
    
    {FuzzyApproximation(D,method = "Naive",piecewise = TRUE)}
  )
  
  
  
})




test_that("Function reports errors", {
  
  # starting values
  
  A <- FuzzyNumbers::FuzzyNumber(-5, 3, 6, 20, left=function(x)
    pbeta(x,0.4,3),
    right=function(x) 1-x^(1/4),
    lower=function(alpha) qbeta(alpha,0.4,3),
    upper=function(alpha) (1-alpha)^4)
  
  B <- FuzzyNumbers::TrapezoidalFuzzyNumber(1,1.5,6,8)
  
  C <- FuzzyNumbers::TrapezoidalFuzzyNumber(-1,2,2,7)
  
  D <- FuzzyNumbers::PiecewiseLinearFuzzyNumber(1, 2, 3, 4,
                                                knot.n=1, knot.alpha=0.25, knot.left=1.5, knot.right=3.25)
  # tests
  
  expect_error(FuzzyApproximation(0.3),
               
               "Parameter value should be a single fuzzy number!")
  
  
  expect_error(FuzzyApproximation(c(0.3,0.5,11)),
               
               "Parameter value should be a single fuzzy number!")
  
  
  expect_error(FuzzyApproximation(A,method = "b"),
               
               "Parameter method should be a proper name of approximation method!")
  
  expect_error(FuzzyApproximation(A,method = 12),
               
               "Parameter method should be a proper name of approximation method!")
  
  expect_error(FuzzyApproximation(A,method = "Naive",piecewise = "c"),
               
               "Parameter piecewise should be a single logical value!")
  
  expect_error(FuzzyApproximation(A,method = "Naive",piecewise = c(TRUE,FALSE)),
               
               "Parameter piecewise should be a single logical value!")
  
  expect_error(FuzzyApproximation(A,method = c("Naive","ExpectedIntervalPreserving")),
               
               "Parameter method should be a single value!")
  
  
  
  
})