decimal/decimal_test.go

package decimal

import (
	"math"
	"testing"
)

var testTable = map[float64]string{
	3.141592653589793:   "3.141592653589793",
	3:                   "3",
	1234567890123456:    "1234567890123456",
	1234567890123456000: "1234567890123456000",
	1234.567890123456:   "1234.567890123456",
	.1234567890123456:   "0.1234567890123456",
	0:                   "0",
	.1111111111111110:   "0.111111111111111",
	.1111111111111111:   "0.1111111111111111",
	.1111111111111119:   "0.1111111111111119",
	.000000000000000001: "0.000000000000000001",
	.000000000000000002: "0.000000000000000002",
	.000000000000000003: "0.000000000000000003",
	.000000000000000005: "0.000000000000000005",
	.000000000000000008: "0.000000000000000008",
	.1000000000000001:   "0.1000000000000001",
	.1000000000000002:   "0.1000000000000002",
	.1000000000000003:   "0.1000000000000003",
	.1000000000000005:   "0.1000000000000005",
	.1000000000000008:   "0.1000000000000008",
}

func TestNewFromFloat(t *testing.T) {
	// add negatives
	for f, s := range testTable {
		if f > 0 {
			testTable[-f] = "-" + s
		}
	}

	for f, s := range testTable {
		d := NewFromFloat(f)
		if d.String() != s {
			t.Errorf("expected %s, got %s (%s, %d)",
				s, d.String(),
				d.value.String(), d.exp)
		}
	}

	shouldPanicOn := []float64{
		math.NaN(),
		math.Inf(1),
		math.Inf(-1),
	}

	for _, n := range shouldPanicOn {
		var d Decimal
		if !didPanic(func() { d = NewFromFloat(n) }) {
			t.Fatalf("Expected panic when creating a Decimal from %v, got %v instead", n, d.String())
		}
	}
}

func TestNewFromString(t *testing.T) {
	// add negatives
	for f, s := range testTable {
		if f > 0 {
			testTable[-f] = "-" + s
		}
	}

	for _, s := range testTable {
		d, err := NewFromString(s)
		if err != nil {
			t.Errorf("error while parsing %s", s)
		} else if d.String() != s {
			t.Errorf("expected %s, got %s (%s, %d)",
				s, d.String(),
				d.value.String(), d.exp)
		}
	}
}

func TestNewFromStringErrs(t *testing.T) {
	tests := []string{
		"",
		"qwert",
		"-",
		".",
		"-.",
		".-",
		"234-.56",
		"234-56",
		"2-",
		"..",
		"2..",
		"..2",
		".5.2",
		"8..2",
		"8.1.",
	}

	for _, s := range tests {
		_, err := NewFromString(s)

		if err == nil {
			t.Errorf("error expected when parsing %s", s)
		}
	}
}

func TestNewFromFloatWithExponent(t *testing.T) {
	type Inp struct {
		float float64
		exp   int32
	}
	tests := map[Inp]string{
		Inp{123.4, -3}:      "123.4",
		Inp{123.4, -1}:      "123.4",
		Inp{123.412345, 1}:  "120",
		Inp{123.412345, 0}:  "123",
		Inp{123.412345, -5}: "123.41235",
		Inp{123.412345, -6}: "123.412345",
		Inp{123.412345, -7}: "123.412345",
	}

	// add negatives
	for p, s := range tests {
		if p.float > 0 {
			tests[Inp{-p.float, p.exp}] = "-" + s
		}
	}

	for input, s := range tests {
		d := NewFromFloatWithExponent(input.float, input.exp)
		if d.String() != s {
			t.Errorf("expected %s, got %s (%s, %d)",
				s, d.String(),
				d.value.String(), d.exp)
		}
	}

	shouldPanicOn := []float64{
		math.NaN(),
		math.Inf(1),
		math.Inf(-1),
	}

	for _, n := range shouldPanicOn {
		var d Decimal
		if !didPanic(func() { d = NewFromFloatWithExponent(n, 0) }) {
			t.Fatalf("Expected panic when creating a Decimal from %v, got %v instead", n, d.String())
		}
	}
}

func TestDecimal_rescale(t *testing.T) {
	type Inp struct {
		int     int64
		exp     int32
		rescale int32
	}
	tests := map[Inp]string{
		Inp{1234, -3, -5}: "1.234",
		Inp{1234, -3, 0}:  "1",
		Inp{1234, 3, 0}:   "1234000",
		Inp{1234, -4, -4}: "0.1234",
	}

	// add negatives
	for p, s := range tests {
		if p.int > 0 {
			tests[Inp{-p.int, p.exp, p.rescale}] = "-" + s
		}
	}

	for input, s := range tests {
		d := New(input.int, input.exp).rescale(input.rescale)

		if d.String() != s {
			t.Errorf("expected %s, got %s (%s, %d)",
				s, d.String(),
				d.value.String(), d.exp)
		}

		// test StringScaled
		s2 := New(input.int, input.exp).StringScaled(input.rescale)
		if s2 != s {
			t.Errorf("expected %s, got %s", s, s2)
		}
	}
}

func TestDecimal_Uninitialized(t *testing.T) {
	a := Decimal{}
	b := Decimal{}

	decs := []Decimal{
		a,
		a.rescale(10),
		a.Abs(),
		a.Add(b),
		a.Sub(b),
		a.Mul(b),
		a.Div(New(1, -1)),
	}

	for _, d := range decs {
		if d.String() != "0" {
			t.Errorf("expected 0, got %s", d.String())
		}
	}

	if a.Cmp(b) != 0 {
		t.Errorf("a != b")
	}
	if a.Exponent() != 0 {
		t.Errorf("a.Exponent() != 0")
	}
}

func TestDecimal_Add(t *testing.T) {
	type Inp struct {
		a string
		b string
	}

	inputs := map[Inp]string{
		Inp{"2", "3"}:                     "5",
		Inp{"2454495034", "3451204593"}:   "5905699627",
		Inp{"24544.95034", ".3451204593"}: "24545.2954604593",
		Inp{".1", ".1"}:                   "0.2",
		Inp{".1", "-.1"}:                  "0",
		Inp{"0", "1.001"}:                 "1.001",
	}

	for inp, res := range inputs {
		a, err := NewFromString(inp.a)
		if err != nil {
			t.FailNow()
		}
		b, err := NewFromString(inp.b)
		if err != nil {
			t.FailNow()
		}
		c := a.Add(b)
		if c.String() != res {
			t.Errorf("expected %s, got %s", res, c.String())
		}
	}
}

func TestDecimal_Sub(t *testing.T) {
	type Inp struct {
		a string
		b string
	}

	inputs := map[Inp]string{
		Inp{"2", "3"}:                     "-1",
		Inp{"12", "3"}:                    "9",
		Inp{"-2", "9"}:                    "-11",
		Inp{"2454495034", "3451204593"}:   "-996709559",
		Inp{"24544.95034", ".3451204593"}: "24544.6052195407",
		Inp{".1", "-.1"}:                  "0.2",
		Inp{".1", ".1"}:                   "0",
		Inp{"0", "1.001"}:                 "-1.001",
		Inp{"1.001", "0"}:                 "1.001",
		Inp{"2.3", ".3"}:                  "2",
	}

	for inp, res := range inputs {
		a, err := NewFromString(inp.a)
		if err != nil {
			t.FailNow()
		}
		b, err := NewFromString(inp.b)
		if err != nil {
			t.FailNow()
		}
		c := a.Sub(b)
		if c.String() != res {
			t.Errorf("expected %s, got %s", res, c.String())
		}
	}
}

func TestDecimal_Mul(t *testing.T) {
	type Inp struct {
		a string
		b string
	}

	inputs := map[Inp]string{
		Inp{"2", "3"}:                     "6",
		Inp{"2454495034", "3451204593"}:   "8470964534836491162",
		Inp{"24544.95034", ".3451204593"}: "8470.964534836491162",
		Inp{".1", ".1"}:                   "0.01",
		Inp{"0", "1.001"}:                 "0",
	}

	for inp, res := range inputs {
		a, err := NewFromString(inp.a)
		if err != nil {
			t.FailNow()
		}
		b, err := NewFromString(inp.b)
		if err != nil {
			t.FailNow()
		}
		c := a.Mul(b)
		if c.String() != res {
			t.Errorf("expected %s, got %s", res, c.String())
		}
	}

	// positive scale
	c := New(1234, 5).Mul(New(45, -1))
	if c.String() != "555300000" {
		t.Errorf("Expected %s, got %s", "555300000", c.String())
	}
}

func TestDecimal_Div(t *testing.T) {
	type Inp struct {
		a string
		b string
	}

	inputs := map[Inp]string{
		Inp{"6", "3"}:                            "2",
		Inp{"10", "2"}:                           "5",
		Inp{"2.2", "1.1"}:                        "2",
		Inp{"-2.2", "-1.1"}:                      "2",
		Inp{"12.88", "5.6"}:                      "2.3",
		Inp{"1023427554493", "43432632"}:         "23563.5628642767953828", // rounded
		Inp{"1", "434324545566634"}:              "0.0000000000000023",
		Inp{"1", "3"}:                            "0.3333333333333333",
		Inp{"2", "3"}:                            "0.6666666666666667", // rounded
		Inp{"10000", "3"}:                        "3333.3333333333333333",
		Inp{"10234274355545544493", "-3"}:        "-3411424785181848164.3333333333333333",
		Inp{"-4612301402398.4753343454", "23.5"}: "-196268144782.9138440146978723",
	}

	for inp, expected := range inputs {
		num, err := NewFromString(inp.a)
		if err != nil {
			t.FailNow()
		}
		denom, err := NewFromString(inp.b)
		if err != nil {
			t.FailNow()
		}
		got := num.Div(denom)
		if got.String() != expected {
			t.Errorf("expected %s when dividing %v by %v, got %v",
				expected, num, denom, got)
		}
	}

	type Inp2 struct {
		n    int64
		exp  int32
		n2   int64
		exp2 int32
	}

	// test code path where exp > 0
	inputs2 := map[Inp2]string{
		Inp2{124, 10, 3, 1}: "41333333333.3333333333333333",
		Inp2{124, 10, 3, 0}: "413333333333.3333333333333333",
		Inp2{124, 10, 6, 1}: "20666666666.6666666666666667",
		Inp2{124, 10, 6, 0}: "206666666666.6666666666666667",
		Inp2{10, 10, 10, 1}: "1000000000",
	}

	for inp, expectedAbs := range inputs2 {
		for i := -1; i <= 1; i += 2 {
			for j := -1; j <= 1; j += 2 {
				n := inp.n * int64(i)
				n2 := inp.n2 * int64(j)
				num := New(n, inp.exp)
				denom := New(n2, inp.exp2)
				expected := expectedAbs
				if i != j {
					expected = "-" + expectedAbs
				}
				got := num.Div(denom)
				if got.String() != expected {
					t.Errorf("expected %s when dividing %v by %v, got %v",
						expected, num, denom, got)
				}
			}
		}
	}
}

func TestDecimal_Overflow(t *testing.T) {
	if !didPanic(func() { New(1, math.MinInt32).Mul(New(1, math.MinInt32)) }) {
		t.Fatalf("should have gotten an overflow panic")
	}
	if !didPanic(func() { New(1, math.MaxInt32).Mul(New(1, math.MaxInt32)) }) {
		t.Fatalf("should have gotten an overflow panic")
	}
}

// old tests after this line

func TestDecimal_Scale(t *testing.T) {
	a := New(1234, -3)
	if a.Exponent() != -3 {
		t.Errorf("error")
	}
}

func TestDecimal_Abs1(t *testing.T) {
	a := New(-1234, -4)
	b := New(1234, -4)

	c := a.Abs()
	if c.Cmp(b) != 0 {
		t.Errorf("error")
	}
}

func TestDecimal_Abs2(t *testing.T) {
	a := New(-1234, -4)
	b := New(1234, -4)

	c := b.Abs()
	if c.Cmp(a) == 0 {
		t.Errorf("error")
	}
}

func TestDecimal_Cmp1(t *testing.T) {
	a := New(123, 3)
	b := New(-1234, 2)

	if a.Cmp(b) != 1 {
		t.Errorf("Error")
	}
}

func TestDecimal_Cmp2(t *testing.T) {
	a := New(123, 3)
	b := New(1234, 2)

	if a.Cmp(b) != -1 {
		t.Errorf("Error")
	}
}

func didPanic(f func()) bool {
	ret := false
	func() {

		defer func() {
			if message := recover(); message != nil {
				ret = true
			}
		}()

		// call the target function
		f()

	}()

	return ret

}