// Copyright 2020 PingCAP, Inc. // // 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, // See the License for the specific language governing permissions and // limitations under the License. package expression import ( "time" "github.com/pingcap/check" ) func (s *testExpressionSuite) TestRandWithTime(c *check.C) { rng1 := NewWithTime() // NOTE: On windows platform, this Sleep is necessary. Because time.Now() is // imprecise, calling UnixNano() twice returns the same value. We have to make // sure the elapsed time is longer than 1ms to get different values. time.Sleep(time.Millisecond) rng2 := NewWithTime() got1 := rng1.Gen() got2 := rng2.Gen() c.Assert(got1 < 1.0, check.IsTrue) c.Assert(got1 >= 0.0, check.IsTrue) c.Assert(got1 != rng1.Gen(), check.IsTrue) c.Assert(got2 < 1.0, check.IsTrue) c.Assert(got2 >= 0.0, check.IsTrue) c.Assert(got2 != rng2.Gen(), check.IsTrue) c.Assert(got1 != got2, check.IsTrue) } func (s *testExpressionSuite) TestRandWithSeed(c *check.C) { tests := [4]struct { seed int64 once float64 twice float64 }{{0, 0.15522042769493574, 0.620881741513388}, {1, 0.40540353712197724, 0.8716141803857071}, {-1, 0.9050373219931845, 0.37014932126752037}, {9223372036854775807, 0.9050373219931845, 0.37014932126752037}} for _, test := range tests { rng := NewWithSeed(test.seed) got1 := rng.Gen() c.Assert(got1 == test.once, check.IsTrue) got2 := rng.Gen() c.Assert(got2 == test.twice, check.IsTrue) } }