| package stats |
| |
| import ( |
| "testing" |
| |
| "github.com/stretchr/testify/assert" |
| "github.com/stretchr/testify/require" |
| ) |
| |
| const almostEqualDelta = 1e-6 |
| |
| func TestNewWilcoxonDistribution_GivenNLessThan0_ReturnsError(t *testing.T) { |
| dist, err := newWilcoxonDistribution(-1) |
| assert.Error(t, err) |
| assert.Nil(t, dist) |
| } |
| |
| func TestPSignRank_GivenValidInputs_ReturnsCorrectResult(t *testing.T) { |
| test := func(name string, x float64, n int, lowerTail bool, expected float64) { |
| t.Run(name, func(t *testing.T) { |
| dist, err := newWilcoxonDistribution(n) |
| require.NoError(t, err) |
| |
| p := dist.pSignRank(x, lowerTail) |
| assert.InDelta(t, expected, p, almostEqualDelta) |
| }) |
| } |
| test("x < 0 and lowerTail = true, returns 0", -1.0, 2, true, 0) |
| test("x < 0 and lowerTail = false, returns 1", -1.0, 2, false, 1) |
| test("x is large and lowerTail = true, returns 1", 55.0, 5, true, 1) |
| test("x is large and lowerTail = false, returns 0", 55.0, 5, false, 0) |
| test("1 <= x <= n*(n+1)/2 and lowerTail = true, returns 1", 5.0, 5, true, 0.3125) |
| test("1 <= x <= n*(n+1)/2 and lowerTail = false, returns 1", 8.0, 4, false, 0.125) |
| } |
| |
| func TestQSignRank_GivenNegativeX_ReturnsError(t *testing.T) { |
| const x = -0.0001 |
| test := func(name string, n int) { |
| t.Run(name, func(t *testing.T) { |
| dist, err := newWilcoxonDistribution(n) |
| require.NoError(t, err) |
| |
| q, err := dist.qSignRank(x, false) |
| require.Error(t, err) |
| assert.Zero(t, q) |
| |
| q, err = dist.qSignRank(x, true) |
| require.Error(t, err) |
| assert.Zero(t, q) |
| }) |
| } |
| test("n = 5, returns error", 5) |
| test("n = 10, returns error", 10) |
| test("n = 30, returns error", 30) |
| } |
| |
| func TestQSignRank_GivenXGreaterThan1_ReturnsError(t *testing.T) { |
| const x = 1.00001 |
| test := func(name string, n int) { |
| t.Run(name, func(t *testing.T) { |
| dist, err := newWilcoxonDistribution(n) |
| require.NoError(t, err) |
| |
| q, err := dist.qSignRank(x, false) |
| require.Error(t, err) |
| assert.Zero(t, q) |
| |
| q, err = dist.qSignRank(x, true) |
| require.Error(t, err) |
| assert.Zero(t, q) |
| }) |
| } |
| test("n = 5, returns error", 5) |
| test("n = 10, returns error", 10) |
| test("n = 30, returns error", 30) |
| } |
| |
| func TestQSignRank_GivenValidInputs_ReturnsCorrectResult(t *testing.T) { |
| test := func(name string, x float64, n int, lowerTail bool, expected float64) { |
| t.Run(name, func(t *testing.T) { |
| dist, err := newWilcoxonDistribution(n) |
| require.NoError(t, err) |
| |
| q, err := dist.qSignRank(x, lowerTail) |
| require.NoError(t, err) |
| assert.InDelta(t, expected, q, almostEqualDelta) |
| }) |
| } |
| test("x = 0, n is even, and lowerTail = true, returns 0", 0, 4, true, 0) |
| test("x = 0, n is even, and lowerTail = false, returns 10", 0, 4, false, 10) |
| test("x = 1, n is even, and lowerTail = true, returns 10", 1, 4, true, 10) |
| test("x = 1, n is even, and lowerTail = false, returns 0", 1, 4, false, 0) |
| test("x = 1, n is odd, and lowerTail = false, returns 15", 0, 5, false, 15) |
| test("0 < x < 1, n is odd, lowerTail = true, returns 3", 0.52158, 3, true, 3) |
| test("0 < x < 1, n is odd, lowerTail = false, returns 4", 0.798382, 5, false, 4) |
| } |
