range_test.go

package go2linq

import (
	"errors"
	"fmt"
	"iter"
	"math"
	"testing"

	"github.com/solsw/iterhelper"
)

// https://github.com/jskeet/edulinq/blob/master/src/Edulinq.Tests/RangeTest.cs

func TestRange(t *testing.T) {
	type args struct {
		start int
		count int
	}
	tests := []struct {
		name        string
		args        args
		want        iter.Seq[int]
		wantErr     bool
		expectedErr error
	}{
		{name: "NegativeCount",
			args: args{
				start: 10,
				count: -1,
			},
			wantErr:     true,
			expectedErr: ErrNegativeCount,
		},
		{name: "ValidRange",
			args: args{
				start: 5,
				count: 3,
			},
			want: iterhelper.VarSeq(5, 6, 7),
		},
		{name: "NegativeStart",
			args: args{
				start: -2,
				count: 5,
			},
			want: iterhelper.VarSeq(-2, -1, 0, 1, 2),
		},
		{name: "EmptyRange",
			args: args{
				start: 100,
				count: 0,
			},
			want: Empty[int](),
		},
		{name: "SingleValueOfMaxInt32",
			args: args{
				start: math.MaxInt32,
				count: 1,
			},
			want: iterhelper.VarSeq(math.MaxInt32),
		},
		{name: "EmptyRangeStartingAtMinInt32",
			args: args{
				start: math.MinInt32,
				count: 0,
			},
			want: Empty[int](),
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got, err := Range(tt.args.start, tt.args.count)
			if (err != nil) != tt.wantErr {
				t.Errorf("Range() error = %v, wantErr %v", err, tt.wantErr)
				return
			}
			if tt.wantErr {
				if !errors.Is(err, tt.expectedErr) {
					t.Errorf("Range() error = %v, expectedErr %v", err, tt.expectedErr)
				}
				return
			}
			equal, _ := SequenceEqual(got, tt.want)
			if !equal {
				t.Errorf("Range() = %v, want %v", iterhelper.StringDef(got), iterhelper.StringDef(tt.want))
			}
		})
	}
}

// example from
// https://learn.microsoft.com/dotnet/api/system.linq.enumerable.range#examples
func ExampleRange() {
	// Generate a sequence of integers from 1 to 10 and then select their squares.
	rnge, _ := Range(1, 10)
	squares, _ := Select(rnge, func(x int) int { return x * x })
	for num := range squares {
		fmt.Println(num)
	}
	// Output:
	// 1
	// 4
	// 9
	// 16
	// 25
	// 36
	// 49
	// 64
	// 81
	// 100
}