pipoint/filter_test.go

// Copyright 2017 Google 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,
// 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 pipoint

import (
	"testing"

	"github.com/stretchr/testify/assert"
)

func TestLowpass(t *testing.T) {
	tau := 0.3
	l := &Lowpass{}

	// Moves towards the input in diminishing steps.
	assert.InDelta(t, l.StepEx(3, tau), 0.9, 0.1)
	assert.InDelta(t, l.StepEx(3, tau), 1.6, 0.1)
	assert.InDelta(t, l.StepEx(3, tau), 2.0, 0.1)
	assert.InDelta(t, l.StepEx(3, tau), 2.3, 0.1)
	assert.InDelta(t, l.StepEx(3, tau), 2.5, 0.1)
}

func TestLinPred(t *testing.T) {
	l := &LinPred{}

	// Returns initial value.
	l.SetEx(5, 1, 1)
	assert.InDelta(t, l.GetEx(1), 5, 0.001)
	// Initial value continues.
	assert.InDelta(t, l.GetEx(2), 5, 0.001)

	l.SetEx(5.5, 2, 2)
	// Initially returns the same value.
	assert.InDelta(t, l.GetEx(2), 5.5, 0.001)
	// Velocity is 0.5/s
	assert.InDelta(t, l.GetEx(2.5), 5.75, 0.001)
	assert.InDelta(t, l.GetEx(3.0), 6.0, 0.001)

	// Negative velocity also works.
	l.SetEx(4, 3, 3)
	assert.InDelta(t, l.GetEx(3), 4, 0.001)
	assert.InDelta(t, l.GetEx(4), 2.5, 0.001)
}