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// Copyright The OpenTelemetry Authors
// SPDX-License-Identifier: Apache-2.0
package consistent
import (
"testing"
"github.com/stretchr/testify/require"
)
func TestSplitProb(t *testing.T) {
require.Equal(t, -1, expFromFloat64(0.6)) //nolint:testifylint // false positive on expected-actual
require.Equal(t, -2, expFromFloat64(0.4)) //nolint:testifylint // false positive on expected-actual
require.Equal(t, 0.5, expToFloat64(-1))
require.Equal(t, 0.25, expToFloat64(-2))
for _, tc := range []struct {
in float64
low uint8
lowProb float64
}{
// Probability 0.75 corresponds with choosing S=1 (the
// "low" probability) 50% of the time and S=0 (the
// "high" probability) 50% of the time.
{0.75, 1, 0.5},
{0.6, 1, 0.8},
{0.9, 1, 0.2},
// Powers of 2 exactly
{1, 0, 1},
{0.5, 1, 1},
{0.25, 2, 1},
// Smaller numbers
{0.05, 5, 0.4},
{0.1, 4, 0.4}, // 0.1 == 0.4 * 1/16 + 0.6 * 1/8
{0.003, 9, 0.464},
// Special cases:
{0, 63, 1},
} {
low, high, lowProb := splitProb(tc.in)
require.Equal(t, tc.low, low, "got %v want %v", low, tc.low)
if lowProb != 1 {
require.Equal(t, tc.low-1, high, "got %v want %v", high, tc.low-1)
}
require.InEpsilon(t, tc.lowProb, lowProb, 1e-6, "got %v want %v", lowProb, tc.lowProb)
}
}
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