initial checkin

Signed-off-by: Dr. Carsten Leue <carsten.leue@de.ibm.com>

either/either_test.go

@@ -0,0 +1,96 @@
+package either
+
+import (
+	"errors"
+	"testing"
+
+	F "github.com/ibm/fp-go/function"
+	"github.com/ibm/fp-go/internal/utils"
+	O "github.com/ibm/fp-go/option"
+	S "github.com/ibm/fp-go/string"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestIsLeft(t *testing.T) {
+	err := errors.New("Some error")
+	withError := Left[error, string](err)
+
+	assert.True(t, IsLeft(withError))
+	assert.False(t, IsRight(withError))
+}
+
+func TestIsRight(t *testing.T) {
+	noError := Right[error]("Carsten")
+
+	assert.True(t, IsRight(noError))
+	assert.False(t, IsLeft(noError))
+}
+
+func TestMapEither(t *testing.T) {
+
+	assert.Equal(t, F.Pipe1(Right[error]("abc"), Map[error](utils.StringLen)), Right[error](3))
+
+	val2 := F.Pipe1(Left[string, string]("s"), Map[string](utils.StringLen))
+	exp2 := Left[string, int]("s")
+
+	assert.Equal(t, val2, exp2)
+}
+
+func TestUnwrapError(t *testing.T) {
+	a := ""
+	err := errors.New("Some error")
+	withError := Left[error, string](err)
+
+	res, extracted := UnwrapError(withError)
+	assert.Equal(t, a, res)
+	assert.Equal(t, extracted, err)
+
+}
+
+func TestReduce(t *testing.T) {
+
+	s := S.Semigroup()
+
+	assert.Equal(t, "foobar", F.Pipe1(Right[string]("bar"), Reduce[string](s.Concat, "foo")))
+	assert.Equal(t, "foo", F.Pipe1(Left[string, string]("bar"), Reduce[string](s.Concat, "foo")))
+
+}
+
+func TestAp(t *testing.T) {
+	f := S.Size
+
+	assert.Equal(t, Right[string](3), F.Pipe1(Right[string](f), Ap[string, string, int](Right[string]("abc"))))
+	assert.Equal(t, Left[string, int]("maError"), F.Pipe1(Right[string](f), Ap[string, string, int](Left[string, string]("maError"))))
+	assert.Equal(t, Left[string, int]("mabError"), F.Pipe1(Left[string, func(string) int]("mabError"), Ap[string, string, int](Left[string, string]("maError"))))
+}
+
+func TestAlt(t *testing.T) {
+	assert.Equal(t, Right[string](1), F.Pipe1(Right[string](1), Alt(F.Constant(Right[string](2)))))
+	assert.Equal(t, Right[string](1), F.Pipe1(Right[string](1), Alt(F.Constant(Left[string, int]("a")))))
+	assert.Equal(t, Right[string](2), F.Pipe1(Left[string, int]("b"), Alt(F.Constant(Right[string](2)))))
+	assert.Equal(t, Left[string, int]("b"), F.Pipe1(Left[string, int]("a"), Alt(F.Constant(Left[string, int]("b")))))
+}
+
+func TestChainFirst(t *testing.T) {
+	f := F.Flow2(S.Size, Right[string, int])
+
+	assert.Equal(t, Right[string]("abc"), F.Pipe1(Right[string]("abc"), ChainFirst(f)))
+	assert.Equal(t, Left[string, string]("maError"), F.Pipe1(Left[string, string]("maError"), ChainFirst(f)))
+}
+
+func TestChainOptionK(t *testing.T) {
+	f := ChainOptionK[string, int, int](F.Constant("a"))(func(n int) O.Option[int] {
+		if n > 0 {
+			return O.Some(n)
+		}
+		return O.None[int]()
+	})
+	assert.Equal(t, Right[string](1), f(Right[string](1)))
+	assert.Equal(t, Left[string, int]("a"), f(Right[string](-1)))
+	assert.Equal(t, Left[string, int]("b"), f(Left[string, int]("b")))
+}
+
+func TestFromOption(t *testing.T) {
+	assert.Equal(t, Left[string, int]("none"), FromOption[string, int](F.Constant("none"))(O.None[int]()))
+	assert.Equal(t, Right[string](1), FromOption[string, int](F.Constant("none"))(O.Some(1)))
+}