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| 1 | +/* |
| 2 | + * Licensed to the Apache Software Foundation (ASF) under one or more |
| 3 | + * contributor license agreements. See the NOTICE file distributed with |
| 4 | + * this work for additional information regarding copyright ownership. |
| 5 | + * The ASF licenses this file to you under the Apache License, Version 2.0 |
| 6 | + * (the "License"); you may not use this file except in compliance with |
| 7 | + * the License. You may obtain a copy of the License at |
| 8 | + * |
| 9 | + * http://www.apache.org/licenses/LICENSE-2.0 |
| 10 | + * |
| 11 | + * Unless required by applicable law or agreed to in writing, software |
| 12 | + * distributed under the License is distributed on an "AS IS" BASIS, |
| 13 | + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 14 | + * See the License for the specific language governing permissions and |
| 15 | + * limitations under the License. |
| 16 | + */ |
| 17 | + |
| 18 | +package org.apache.jorphan.collections |
| 19 | + |
| 20 | +import org.junit.jupiter.api.Assertions.assertEquals |
| 21 | +import org.junit.jupiter.api.Assertions.assertFalse |
| 22 | +import org.junit.jupiter.api.Assertions.assertThrows |
| 23 | +import org.junit.jupiter.api.Assertions.assertTrue |
| 24 | +import org.junit.jupiter.api.Test |
| 25 | + |
| 26 | +class FilterIteratorTest { |
| 27 | + |
| 28 | + private fun <T> assertFilteredResults(collection: Collection<T>, predicate: (T) -> Boolean) { |
| 29 | + assertEquals( |
| 30 | + collection.filter(predicate).toList().toString(), |
| 31 | + FilterIterator(collection.iterator(), predicate).asSequence().toList().toString(), |
| 32 | + ) { |
| 33 | + "input: ${collection.toList()}" |
| 34 | + } |
| 35 | + } |
| 36 | + |
| 37 | + @Test |
| 38 | + fun `filter even numbers from list`() { |
| 39 | + val numbers = listOf(1, 2, 3, 4, 5, 6, 7, 8, 9, 10) |
| 40 | + |
| 41 | + assertFilteredResults(numbers) { it % 2 == 0 } |
| 42 | + } |
| 43 | + |
| 44 | + @Test |
| 45 | + fun `filter odd numbers from list`() { |
| 46 | + val numbers = listOf(1, 2, 3, 4, 5, 6, 7, 8, 9, 10) |
| 47 | + |
| 48 | + assertFilteredResults(numbers) { it % 2 != 0 } |
| 49 | + } |
| 50 | + |
| 51 | + @Test |
| 52 | + fun `filter strings by length`() { |
| 53 | + val words = listOf("a", "ab", "abc", "abcd", "abcde") |
| 54 | + assertFilteredResults(words) { it.length > 2 } |
| 55 | + } |
| 56 | + |
| 57 | + @Test |
| 58 | + fun `filter with no matches returns empty iterator`() { |
| 59 | + val numbers = listOf(1, 3, 5, 7, 9) |
| 60 | + assertFilteredResults(numbers) { it % 2 == 0 } |
| 61 | + } |
| 62 | + |
| 63 | + @Test |
| 64 | + fun `filter with all matches returns all elements`() { |
| 65 | + val numbers = listOf(2, 4, 6, 8, 10) |
| 66 | + assertFilteredResults(numbers) { it % 2 == 0 } |
| 67 | + } |
| 68 | + |
| 69 | + @Test |
| 70 | + fun `filter empty list returns empty iterator`() { |
| 71 | + val empty = emptyList<Int>() |
| 72 | + assertFilteredResults(empty) { it > 0 } |
| 73 | + } |
| 74 | + |
| 75 | + @Test |
| 76 | + fun `filter with null values`() { |
| 77 | + val items = listOf("a", null, "b", null, "c") |
| 78 | + assertFilteredResults(items) { it != null } |
| 79 | + } |
| 80 | + |
| 81 | + @Test |
| 82 | + fun `filter with always true predicate`() { |
| 83 | + val numbers = listOf(1, 2, 3, 4, 5) |
| 84 | + assertFilteredResults(numbers) { true } |
| 85 | + } |
| 86 | + |
| 87 | + @Test |
| 88 | + fun `filter with always false predicate`() { |
| 89 | + val numbers = listOf(1, 2, 3, 4, 5) |
| 90 | + assertFilteredResults(numbers) { false } |
| 91 | + } |
| 92 | + |
| 93 | + @Test |
| 94 | + fun `calling next without hasNext throws exception`() { |
| 95 | + val numbers = listOf(1, 3, 5) |
| 96 | + val filtered = FilterIterator(numbers.iterator()) { it % 2 == 0 } |
| 97 | + |
| 98 | + assertThrows(NoSuchElementException::class.java) { |
| 99 | + filtered.next() |
| 100 | + } |
| 101 | + } |
| 102 | + |
| 103 | + @Test |
| 104 | + fun `calling next after exhausted throws exception`() { |
| 105 | + val numbers = listOf(2) |
| 106 | + val filtered = FilterIterator(numbers.iterator()) { it % 2 == 0 } |
| 107 | + |
| 108 | + assertTrue(filtered.hasNext()) |
| 109 | + assertEquals(2, filtered.next()) |
| 110 | + assertFalse(filtered.hasNext()) |
| 111 | + |
| 112 | + assertThrows(NoSuchElementException::class.java) { |
| 113 | + filtered.next() |
| 114 | + } |
| 115 | + } |
| 116 | + |
| 117 | + @Test |
| 118 | + fun `multiple calls to hasNext are idempotent`() { |
| 119 | + val numbers = listOf(1, 2, 3, 4, 5) |
| 120 | + val filtered = FilterIterator(numbers.iterator()) { it % 2 == 0 } |
| 121 | + |
| 122 | + assertTrue(filtered.hasNext()) |
| 123 | + assertTrue(filtered.hasNext()) |
| 124 | + assertTrue(filtered.hasNext()) |
| 125 | + assertEquals(2, filtered.next()) |
| 126 | + } |
| 127 | + |
| 128 | + @Test |
| 129 | + fun `filter chain with multiple predicates`() { |
| 130 | + val numbers = listOf(1, 2, 3, 4, 5, 6, 7, 8, 9, 10) |
| 131 | + |
| 132 | + // Filter even numbers, then filter those > 5 |
| 133 | + val filtered1 = FilterIterator(numbers.iterator()) { it % 2 == 0 } |
| 134 | + val filtered2 = FilterIterator(filtered1) { it > 5 } |
| 135 | + |
| 136 | + val result = filtered2.asSequence().toList() |
| 137 | + |
| 138 | + assertEquals(listOf(6, 8, 10), result) |
| 139 | + } |
| 140 | + |
| 141 | + @Test |
| 142 | + fun `filter with single element matching`() { |
| 143 | + val numbers = listOf(1, 2, 3) |
| 144 | + val filtered = FilterIterator(numbers.iterator()) { it == 2 } |
| 145 | + |
| 146 | + assertTrue(filtered.hasNext()) |
| 147 | + assertEquals(2, filtered.next()) |
| 148 | + assertFalse(filtered.hasNext()) |
| 149 | + } |
| 150 | +} |
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