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56 lines
1.8 KiB
56 lines
1.8 KiB
// Copyright 2020 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package expression
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import (
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"time"
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"github.com/pingcap/check"
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)
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func (s *testExpressionSuite) TestRandWithTime(c *check.C) {
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rng1 := NewWithTime()
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// NOTE: On windows platform, this Sleep is necessary. Because time.Now() is
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// imprecise, calling UnixNano() twice returns the same value. We have to make
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// sure the elapsed time is longer than 1ms to get different values.
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time.Sleep(time.Millisecond)
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rng2 := NewWithTime()
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got1 := rng1.Gen()
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got2 := rng2.Gen()
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c.Assert(got1 < 1.0, check.IsTrue)
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c.Assert(got1 >= 0.0, check.IsTrue)
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c.Assert(got1 != rng1.Gen(), check.IsTrue)
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c.Assert(got2 < 1.0, check.IsTrue)
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c.Assert(got2 >= 0.0, check.IsTrue)
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c.Assert(got2 != rng2.Gen(), check.IsTrue)
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c.Assert(got1 != got2, check.IsTrue)
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}
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func (s *testExpressionSuite) TestRandWithSeed(c *check.C) {
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tests := [4]struct {
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seed int64
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once float64
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twice float64
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}{{0, 0.15522042769493574, 0.620881741513388},
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{1, 0.40540353712197724, 0.8716141803857071},
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{-1, 0.9050373219931845, 0.37014932126752037},
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{9223372036854775807, 0.9050373219931845, 0.37014932126752037}}
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for _, test := range tests {
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rng := NewWithSeed(test.seed)
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got1 := rng.Gen()
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c.Assert(got1 == test.once, check.IsTrue)
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got2 := rng.Gen()
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c.Assert(got2 == test.twice, check.IsTrue)
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}
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}
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