#102 Change Range then raises panic if step == 0

bench/range_test.go

@@ -45,7 +45,7 @@ func BenchmarkRange(b *testing.B) {
 		},
 	}
 	for _, tt := range tests {
-		itb, _ := gcf.Range(tt.start, tt.end, tt.step)
+		itb := gcf.Range(tt.start, tt.end, tt.step)
 		c := 0
 		it := itb.Iterator()
 		for it.MoveNext() {

range.go

@@ -32,23 +32,23 @@ type rangeDecrementIterator[T constraints.Integer] struct {
 //
 // If step is positive, elements is enumerated from start to end with increment by step.
 // If step is negative, elements is enumerated from start to end with decrement by step.
-// If step is zero, returns error.
+// If step is zero, raises panic.
 // If start equals to end, makes Iterable with one element.
 // If direction of step is opposite to start and end, returns empty Iterable.
-func Range[T constraints.Integer](start, end, step T) (Iterable[T], error) {
+func Range[T constraints.Integer](start, end, step T) Iterable[T] {
 	if step == 0 {
-		return nil, errStep0
+		panic("step for Range must not be zero.")
 	}
 	if start == end {
-		return FromSlice([]T{start}), nil
+		return FromSlice([]T{start})
 	}
 	if step > 0 && start > end {
-		return empty[T](), nil
+		return empty[T]()
 	}
 	if step < 0 && start < end {
-		return empty[T](), nil
+		return empty[T]()
 	}
-	return &rangeIterable[T]{start, end, step}, nil
+	return &rangeIterable[T]{start, end, step}
 }
 
 func (itb *rangeIterable[T]) Iterator() Iterator[T] {

range_test.go

@@ -15,10 +15,10 @@ func TestRange(t *testing.T) {
 		step  int
 	}
 	tests := []struct {
-		name    string
-		args    args
-		wantErr bool
-		want    []int
+		name      string
+		args      args
+		wantPanic bool
+		want      []int
 	}{
 		{
 			name: "positive step",
@@ -117,43 +117,43 @@ func TestRange(t *testing.T) {
 				end:   2,
 				step:  0,
 			},
-			wantErr: true,
+			wantPanic: true,
 		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			assert := assert.New(t)
-			itb, err := gcf.Range(tt.args.start, tt.args.end, tt.args.step)
-			if tt.wantErr {
-				assert.Error(err)
-				assert.Empty(itb)
+			if tt.wantPanic {
+				assert.Panics(func() {
+					_ = gcf.Range(tt.args.start, tt.args.end, tt.args.step)
+				})
 				return
 			}
-			assert.NoError(err)
+			itb := gcf.Range(tt.args.start, tt.args.end, tt.args.step)
 			s := gcf.ToSlice(itb)
 			assert.Equal(tt.want, s)
 		})
 	}
 
-	itb, _ := gcf.Range(1, 3, 1)
+	itb := gcf.Range(1, 3, 1)
 	testBeforeAndAfter(t, itb)
-	itb, _ = gcf.Range(3, 1, -1)
+	itb = gcf.Range(3, 1, -1)
 	testBeforeAndAfter(t, itb)
 
 	testEmpties(t, func(itb gcf.Iterable[int]) gcf.Iterable[int] {
-		itb, _ = gcf.Range(1, 0, 1)
+		itb = gcf.Range(1, 0, 1)
 		return itb
 	})
 	testEmpties(t, func(itb gcf.Iterable[int]) gcf.Iterable[int] {
-		itb, _ = gcf.Range(1, 2, -1)
+		itb = gcf.Range(1, 2, -1)
 		return itb
 	})
 }
 
 func ExampleRange() {
-	itb, _ := gcf.Range(2, 10, 2)
+	itb := gcf.Range(2, 10, 2)
 	fmt.Println(gcf.ToSlice(itb))
-	itb, _ = gcf.Range(10, 1, -2)
+	itb = gcf.Range(10, 1, -2)
 	fmt.Println(gcf.ToSlice(itb))
 	// Output:
 	// [2 4 6 8 10]