Subversion Repositories openrisc

// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package sort_test

import (
        . "sort"
        "testing"
)

func f(a []int, x int) func(int) bool {
        return func(i int) bool {
                return a[i] >= x
        }
}

var data = []int{0: -10, 1: -5, 2: 0, 3: 1, 4: 2, 5: 3, 6: 5, 7: 7, 8: 11, 9: 100, 10: 100, 11: 100, 12: 1000, 13: 10000}

var tests = []struct {
        name string
        n    int
        f    func(int) bool
        i    int
}{
        {"empty", 0, nil, 0},
        {"1 1", 1, func(i int) bool { return i >= 1 }, 1},
        {"1 true", 1, func(i int) bool { return true }, 0},
        {"1 false", 1, func(i int) bool { return false }, 1},
        {"1e9 991", 1e9, func(i int) bool { return i >= 991 }, 991},
        {"1e9 true", 1e9, func(i int) bool { return true }, 0},
        {"1e9 false", 1e9, func(i int) bool { return false }, 1e9},
        {"data -20", len(data), f(data, -20), 0},
        {"data -10", len(data), f(data, -10), 0},
        {"data -9", len(data), f(data, -9), 1},
        {"data -6", len(data), f(data, -6), 1},
        {"data -5", len(data), f(data, -5), 1},
        {"data 3", len(data), f(data, 3), 5},
        {"data 11", len(data), f(data, 11), 8},
        {"data 99", len(data), f(data, 99), 9},
        {"data 100", len(data), f(data, 100), 9},
        {"data 101", len(data), f(data, 101), 12},
        {"data 10000", len(data), f(data, 10000), 13},
        {"data 10001", len(data), f(data, 10001), 14},
        {"descending a", 7, func(i int) bool { return []int{99, 99, 59, 42, 7, 0, -1, -1}[i] <= 7 }, 4},
        {"descending 7", 1e9, func(i int) bool { return 1e9-i <= 7 }, 1e9 - 7},
        {"overflow", 2e9, func(i int) bool { return false }, 2e9},
}

func TestSearch(t *testing.T) {
        for _, e := range tests {
                i := Search(e.n, e.f)
                if i != e.i {
                        t.Errorf("%s: expected index %d; got %d", e.name, e.i, i)
                }
        }
}

// log2 computes the binary logarithm of x, rounded up to the next integer.
// (log2(0) == 0, log2(1) == 0, log2(2) == 1, log2(3) == 2, etc.)
//
func log2(x int) int {
        n := 0
        for p := 1; p < x; p += p {
                // p == 2**n
                n++
        }
        // p/2 < x <= p == 2**n
        return n
}

func TestSearchEfficiency(t *testing.T) {
        n := 100
        step := 1
        for exp := 2; exp < 10; exp++ {
                // n == 10**exp
                // step == 10**(exp-2)
                max := log2(n)
                for x := 0; x < n; x += step {
                        count := 0
                        i := Search(n, func(i int) bool { count++; return i >= x })
                        if i != x {
                                t.Errorf("n = %d: expected index %d; got %d", n, x, i)
                        }
                        if count > max {
                                t.Errorf("n = %d, x = %d: expected <= %d calls; got %d", n, x, max, count)
                        }
                }
                n *= 10
                step *= 10
        }
}

// Smoke tests for convenience wrappers - not comprehensive.

var fdata = []float64{0: -3.14, 1: 0, 2: 1, 3: 2, 4: 1000.7}
var sdata = []string{0: "f", 1: "foo", 2: "foobar", 3: "x"}

var wrappertests = []struct {
        name   string
        result int
        i      int
}{
        {"SearchInts", SearchInts(data, 11), 8},
        {"SearchFloat64s", SearchFloat64s(fdata, 2.1), 4},
        {"SearchStrings", SearchStrings(sdata, ""), 0},
        {"IntSlice.Search", IntSlice(data).Search(0), 2},
        {"Float64Slice.Search", Float64Slice(fdata).Search(2.0), 3},
        {"StringSlice.Search", StringSlice(sdata).Search("x"), 3},
}

func TestSearchWrappers(t *testing.T) {
        for _, e := range wrappertests {
                if e.result != e.i {
                        t.Errorf("%s: expected index %d; got %d", e.name, e.i, e.result)
                }
        }
}

// Abstract exhaustive test: all sizes up to 100,
// all possible return values.  If there are any small
// corner cases, this test exercises them.
func TestSearchExhaustive(t *testing.T) {
        for size := 0; size <= 100; size++ {
                for targ := 0; targ <= size; targ++ {
                        i := Search(size, func(i int) bool { return i >= targ })
                        if i != targ {
                                t.Errorf("Search(%d, %d) = %d", size, targ, i)
                        }
                }
        }
}