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// 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)
}
}