slice.js 1.5 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657
  1. var assert = require('assert');
  2. var slice = require('../lib/slice');
  3. var data = ['a', 'b', 'c', 'd', 'e', 'f'];
  4. suite('slice', function() {
  5. test('no params yields copy', function() {
  6. assert.deepEqual(slice(data), data);
  7. });
  8. test('no end param defaults to end', function() {
  9. assert.deepEqual(slice(data, 2), data.slice(2));
  10. });
  11. test('zero end param yields empty', function() {
  12. assert.deepEqual(slice(data, 0, 0), []);
  13. });
  14. test('first element with explicit params', function() {
  15. assert.deepEqual(slice(data, 0, 1, 1), ['a']);
  16. });
  17. test('last element with explicit params', function() {
  18. assert.deepEqual(slice(data, -1, 6), ['f']);
  19. });
  20. test('empty extents and negative step reverses', function() {
  21. assert.deepEqual(slice(data, null, null, -1), ['f', 'e', 'd', 'c', 'b', 'a']);
  22. });
  23. test('negative step partial slice', function() {
  24. assert.deepEqual(slice(data, 4, 2, -1), ['e', 'd']);
  25. });
  26. test('negative step partial slice no start defaults to end', function() {
  27. assert.deepEqual(slice(data, null, 2, -1), ['f', 'e', 'd']);
  28. });
  29. test('extents clamped end', function() {
  30. assert.deepEqual(slice(data, null, 100), data);
  31. });
  32. test('extents clamped beginning', function() {
  33. assert.deepEqual(slice(data, -100, 100), data);
  34. });
  35. test('backwards extents yields empty', function() {
  36. assert.deepEqual(slice(data, 2, 1), []);
  37. });
  38. test('zero step gets shot down', function() {
  39. assert.throws(function() { slice(data, null, null, 0) });
  40. });
  41. });