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- // Copyright 2017 Google LLC
- //
- // 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.
-
- package distribution
-
- import (
- "sync"
- "testing"
- )
-
- func TestDistribution(t *testing.T) {
- // These tests come from examples in https://en.wikipedia.org/wiki/Percentile#The_nearest-rank_method
- tests := []struct {
- // values in distribution
- vals []int
-
- // percentiles and expected percentile values
- pp []float64
- vv []int
- }{
- {
- vals: []int{15, 20, 35, 40, 50},
- pp: []float64{0.05, 0.3, 0.4, 0.5, 1},
- vv: []int{15, 20, 20, 35, 50},
- },
- {
- vals: []int{3, 6, 7, 8, 8, 10, 13, 15, 16, 20},
- pp: []float64{0.25, 0.5, 0.75, 1},
- vv: []int{7, 8, 15, 20},
- },
- {
- vals: []int{3, 6, 7, 8, 8, 9, 10, 13, 15, 16, 20},
- pp: []float64{0.25, 0.5, 0.75, 1},
- vv: []int{7, 9, 15, 20},
- },
- }
-
- maxVal := 0
- for _, tst := range tests {
- for _, v := range tst.vals {
- if maxVal < v {
- maxVal = v
- }
- }
- }
-
- for _, tst := range tests {
- d := New(maxVal + 1)
- for _, v := range tst.vals {
- d.Record(v)
- }
- for i, p := range tst.pp {
- got, want := d.Percentile(p), tst.vv[i]
- if got != want {
- t.Errorf("d=%v, d.Percentile(%f)=%d, want %d", d, p, got, want)
- }
- }
- }
- }
-
- func TestRace(t *testing.T) {
- const N int = 1e3
- const parallel = 2
-
- d := New(N)
-
- var wg sync.WaitGroup
- wg.Add(parallel)
- for i := 0; i < parallel; i++ {
- go func() {
- for i := 0; i < N; i++ {
- d.Record(i)
- }
- wg.Done()
- }()
- }
-
- for i := 0; i < N; i++ {
- if p := d.Percentile(0.5); p > N {
- t.Fatalf("d.Percentile(0.5)=%d, expected to be at most %d", p, N)
- }
- }
- }
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