ui/ui-text-core/src/test/java/androidx/ui/input/GapBufferTest.kt - platform/frameworks/support - Git at Google

 /*
  * Copyright 2019 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 package androidx.ui.input

 import androidx.test.filters.SmallTest
 import androidx.ui.text.InternalTextApi
 import org.junit.Assert.assertEquals
 import org.junit.Test
 import org.junit.runner.RunWith
 import org.junit.runners.JUnit4
 import kotlin.random.Random

 @OptIn(InternalTextApi::class)
 @SmallTest
 @RunWith(JUnit4::class)
 class GapBufferTest {

     private fun assertStrWithChars(expected: String, pgb: PartialGapBuffer) {
         assertEquals(expected, pgb.toString())
         for (i in 0 until expected.length) {
             assertEquals(expected[i], pgb[i])
         }
     }

     @Test
     fun insertTest_insert_to_empty_string() {
         assertStrWithChars("A", PartialGapBuffer("").apply {
             replace(0, 0, "A")
         })
     }

     @Test
     fun insertTest_insert_and_append() {
         assertStrWithChars("BA", PartialGapBuffer("").apply {
             replace(0, 0, "A")
             replace(0, 0, "B")
         })
     }

     @Test
     fun insertTest_insert_and_prepend() {
         assertStrWithChars("AB", PartialGapBuffer("").apply {
             replace(0, 0, "A")
             replace(1, 1, "B")
         })
     }

     @Test
     fun insertTest_insert_and_insert_into_middle() {
         assertStrWithChars("ABA", PartialGapBuffer("").apply {
             replace(0, 0, "AA")
             replace(1, 1, "B")
         })
     }

     @Test
     fun insertTest_intoExistingText_prepend() {
         assertStrWithChars("AXX", PartialGapBuffer("XX").apply {
             replace(0, 0, "A")
         })
     }

     @Test
     fun insertTest_intoExistingText_insert_into_middle() {
         assertStrWithChars("XAX", PartialGapBuffer("XX").apply {
             replace(1, 1, "A")
         })
     }

     @Test
     fun insertTest_intoExistingText_append() {
         assertStrWithChars("XXA", PartialGapBuffer("XX").apply {
             replace(2, 2, "A")
         })
     }

     @Test
     fun insertTest_intoExistingText_prepend_and_prepend() {
         assertStrWithChars("BAXX", PartialGapBuffer("XX").apply {
             replace(0, 0, "A")
             replace(0, 0, "B")
         })
     }

     @Test
     fun insertTest_intoExistingText_prepend_and_append() {
         assertStrWithChars("ABXX", PartialGapBuffer("XX").apply {
             replace(0, 0, "A")
             replace(1, 1, "B")
         })
     }

     @Test
     fun insertTest_intoExistingText_prepend_and_insert_middle() {
         assertStrWithChars("AXBX", PartialGapBuffer("XX").apply {
             replace(0, 0, "A")
             replace(2, 2, "B")
         })
     }

     @Test
     fun insertTest_intoExistingText_insert_two_chars_and_append() {
         assertStrWithChars("ABAXX", PartialGapBuffer("XX").apply {
             replace(0, 0, "AA")
             replace(1, 1, "B")
         })
     }

     @Test
     fun deleteTest_insert_and_delete_from_head() {
         assertStrWithChars("BC", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(0, 1, "")
         })
     }

     @Test
     fun deleteTest_insert_and_delete_middle() {
         assertStrWithChars("AC", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(1, 2, "")
         })
     }

     @Test
     fun deleteTest_insert_and_delete_tail() {
         assertStrWithChars("AB", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(2, 3, "")
         })
     }

     @Test
     fun deleteTest_insert_and_delete_two_head() {
         assertStrWithChars("C", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(0, 2, "")
         })
     }

     @Test
     fun deleteTest_insert_and_delete_two_tail() {
         assertStrWithChars("A", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(1, 3, "")
         })
     }

     @Test
     fun deleteTest_insert_and_delete_with_two_instruction_from_haed() {
         assertStrWithChars("C", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(0, 1, "")
             replace(0, 1, "")
         })
     }

     @Test
     fun deleteTest_insert_and_delet_with_two_instruction_from_head_and_tail() {
         assertStrWithChars("B", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(0, 1, "")
             replace(1, 2, "")
         })
     }

     @Test
     fun deleteTest_insert_and_delet_with_two_instruction_from_tail() {
         assertStrWithChars("A", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(1, 2, "")
             replace(1, 2, "")
         })
     }

     @Test
     fun deleteTest_insert_and_delete_three_chars() {
         assertStrWithChars("", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(0, 3, "")
         })
     }

     @Test
     fun deleteTest_insert_and_delete_three_chars_with_three_instructions() {
         assertStrWithChars("", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(0, 1, "")
             replace(0, 1, "")
             replace(0, 1, "")
         })
     }

     @Test
     fun deleteTest_fromExistingText_from_head() {
         assertStrWithChars("BC", PartialGapBuffer("ABC").apply {
             replace(0, 1, "")
         })
     }

     @Test
     fun deleteTest_fromExistingText_from_middle() {
         assertStrWithChars("AC", PartialGapBuffer("ABC").apply {
             replace(1, 2, "")
         })
     }

     @Test
     fun deleteTest_fromExistingText_from_tail() {
         assertStrWithChars("AB", PartialGapBuffer("ABC").apply {
             replace(2, 3, "")
         })
     }

     @Test
     fun deleteTest_fromExistingText_delete_two_chars_from_head() {
         assertStrWithChars("C", PartialGapBuffer("ABC").apply {
             replace(0, 2, "")
         })
     }

     @Test
     fun deleteTest_fromExistingText_delete_two_chars_from_tail() {
         assertStrWithChars("A", PartialGapBuffer("ABC").apply {
             replace(1, 3, "")
         })
     }

     @Test
     fun deleteTest_fromExistingText_delete_two_chars_with_two_instruction_from_head() {
         assertStrWithChars("C", PartialGapBuffer("ABC").apply {
             replace(0, 1, "")
             replace(0, 1, "")
         })
     }

     @Test
     fun deleteTest_fromExistingText_delete_two_chars_with_two_instruction_from_head_and_tail() {
         assertStrWithChars("B", PartialGapBuffer("ABC").apply {
             replace(0, 1, "")
             replace(1, 2, "")
         })
     }

     @Test
     fun deleteTest_fromExistingText_delete_two_chars_with_two_instruction_from_tail() {
         assertStrWithChars("A", PartialGapBuffer("ABC").apply {
             replace(1, 2, "")
             replace(1, 2, "")
         })
     }

     @Test
     fun deleteTest_fromExistingText_delete_three_chars() {
         assertStrWithChars("", PartialGapBuffer("ABC").apply {
             replace(0, 3, "")
         })
     }

     @Test
     fun deleteTest_fromExistingText_delete_three_chars_with_three_instructions() {
         assertStrWithChars("", PartialGapBuffer("ABC").apply {
             replace(0, 1, "")
             replace(0, 1, "")
             replace(0, 1, "")
         })
     }

     @Test
     fun replaceTest_head() {
         assertStrWithChars("XBC", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(0, 1, "X")
         })
     }

     @Test
     fun replaceTest_middle() {
         assertStrWithChars("AXC", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(1, 2, "X")
         })
     }

     @Test
     fun replaceTest_tail() {
         assertStrWithChars("ABX", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(2, 3, "X")
         })
     }

     @Test
     fun replaceTest_head_two_chars() {
         assertStrWithChars("XC", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(0, 2, "X")
         })
     }

     @Test
     fun replaceTest_middle_two_chars() {
         assertStrWithChars("AX", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(1, 3, "X")
         })
     }

     @Test
     fun replaceTest_three_chars() {
         assertStrWithChars("X", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(0, 3, "X")
         })
     }

     @Test
     fun replaceTest_one_char_with_two_chars_from_head() {
         assertStrWithChars("XYBC", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(0, 1, "XY")
         })
     }

     @Test
     fun replaceTest_one_char_with_two_chars_from_middle() {
         assertStrWithChars("AXYC", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(1, 2, "XY")
         })
     }

     @Test
     fun replaceTest_one_char_with_two_chars_from_tail() {
         assertStrWithChars("ABXY", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(2, 3, "XY")
         })
     }

     @Test
     fun replaceTest_two_chars_with_two_chars_from_head() {
         assertStrWithChars("XYC", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(0, 2, "XY")
         })
     }

     @Test
     fun replaceTest_two_chars_with_two_chars_from_tail() {
         assertStrWithChars("AXY", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(1, 3, "XY")
         })
     }

     @Test
     fun replaceTest_three_chars_with_two_char() {
         assertStrWithChars("XY", PartialGapBuffer("").apply {
             replace(0, 0, "ABC")
             replace(0, 3, "XY")
         })
     }

     @Test
     fun replaceTest_fromExistingText_head() {
         assertStrWithChars("XBC", PartialGapBuffer("ABC").apply {
             replace(0, 1, "X")
         })
     }

     @Test
     fun replaceTest_fromExistingText_middle() {
         assertStrWithChars("AXC", PartialGapBuffer("ABC").apply {
             replace(1, 2, "X")
         })
     }

     @Test
     fun replaceTest_fromExistingText_tail() {
         assertStrWithChars("ABX", PartialGapBuffer("ABC").apply {
             replace(2, 3, "X")
         })
     }

     @Test
     fun replaceTest_fromExistingText_two_chars_with_one_char_from_head() {
         assertStrWithChars("XC", PartialGapBuffer("ABC").apply {
             replace(0, 2, "X")
         })
     }

     @Test
     fun replaceTest_fromExistingText_two_chars_with_one_char_from_tail() {
         assertStrWithChars("AX", PartialGapBuffer("ABC").apply {
             replace(1, 3, "X")
         })
     }

     @Test
     fun replaceTest_fromExistingText_three_chars() {
         assertStrWithChars("X", PartialGapBuffer("ABC").apply {
             replace(0, 3, "X")
         })
     }

     @Test
     fun replaceTest_fromExistingText_one_char_with_two_chars_from_head() {
         assertStrWithChars("XYBC", PartialGapBuffer("ABC").apply {
             replace(0, 1, "XY")
         })
     }

     @Test
     fun replaceTest_fromExistingText_one_char_with_two_chars_from_middle() {
         assertStrWithChars("AXYC", PartialGapBuffer("ABC").apply {
             replace(1, 2, "XY")
         })
     }

     @Test
     fun replaceTest_fromExistingText_one_char_with_two_chars_from_tail() {
         assertStrWithChars("ABXY", PartialGapBuffer("ABC").apply {
             replace(2, 3, "XY")
         })
     }

     @Test
     fun replaceTest_fromExistingText_two_chars_with_two_chars_from_head() {
         assertStrWithChars("XYC", PartialGapBuffer("ABC").apply {
             replace(0, 2, "XY")
         })
     }

     @Test
     fun replaceTest_fromExistingText_two_chars_with_two_chars_from_tail() {
         assertStrWithChars("AXY", PartialGapBuffer("ABC").apply {
             replace(1, 3, "XY")
         })
     }

     @Test
     fun replaceTest_fromExistingText_three_chars_with_three_chars() {
         assertStrWithChars("XY", PartialGapBuffer("ABC").apply {
             replace(0, 3, "XY")
         })
     }

     // Compare with the result of StringBuffer. We trust the StringBuffer works correctly
     private fun assertReplace(
         start: Int,
         end: Int,
         str: String,
         sb: StringBuffer,
         gb: PartialGapBuffer
     ) {
         sb.replace(start, end, str)
         gb.replace(start, end, str)
         assertStrWithChars(sb.toString(), gb)
     }

     private val LONG_INIT_TEXT = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".repeat(256)
     private val SHORT_TEXT = "A"
     private val MEDIUM_TEXT = "Hello, World"
     private val LONG_TEXT = "abcdefghijklmnopqrstuvwxyz".repeat(16)

     @Test
     fun longTextTest_keep_insertion() {
         val sb = StringBuffer(LONG_INIT_TEXT)
         val gb = PartialGapBuffer(LONG_INIT_TEXT)

         var c = 256 // cursor
         assertReplace(c, c, SHORT_TEXT, sb, gb)
         c += SHORT_TEXT.length
         assertReplace(c, c, MEDIUM_TEXT, sb, gb)
         c += MEDIUM_TEXT.length
         assertReplace(c, c, LONG_TEXT, sb, gb)
         c += LONG_TEXT.length
         assertReplace(c, c, MEDIUM_TEXT, sb, gb)
         c += MEDIUM_TEXT.length
         assertReplace(c, c, SHORT_TEXT, sb, gb)
     }

     @Test
     fun longTextTest_keep_deletion() {
         val sb = StringBuffer(LONG_INIT_TEXT)
         val gb = PartialGapBuffer(LONG_INIT_TEXT)

         var c = 2048 // cursor
         // Forward deletion
         assertReplace(c, c + 10, "", sb, gb)
         assertReplace(c, c + 100, "", sb, gb)
         assertReplace(c, c + 1000, "", sb, gb)

         // Backspacing
         assertReplace(c - 10, c, "", sb, gb)
         c -= 10
         assertReplace(c - 100, c, "", sb, gb)
         c -= 100
         assertReplace(c - 1000, c, "", sb, gb)
     }

     @Test
     fun longTextTest_farInput() {
         val sb = StringBuffer(LONG_INIT_TEXT)
         val gb = PartialGapBuffer(LONG_INIT_TEXT)

         assertReplace(1024, 1024, "Hello, World", sb, gb)
         assertReplace(128, 128, LONG_TEXT, sb, gb)
     }

     @Test
     fun randomInsertDeleteStressTest() {
         val sb = StringBuffer(LONG_INIT_TEXT)
         val gb = PartialGapBuffer(LONG_INIT_TEXT)

         val r = Random(10 /* fix the seed for reproduction */)

         val INSERT_TEXTS = arrayOf(SHORT_TEXT, MEDIUM_TEXT, LONG_TEXT)
         val DEL_LENGTHS = arrayOf(1, 10, 100)

         var c = LONG_INIT_TEXT.length / 2

         for (i in 0..100) {
             when (r.nextInt() % 4) {
                 0 -> { // insert
                     val txt = INSERT_TEXTS.random(r)
                     assertReplace(c, c, txt, sb, gb)
                     c += txt.length
                 }
                 1 -> { // forward delete
                     assertReplace(c, c + DEL_LENGTHS.random(r), "", sb, gb)
                 }
                 2 -> { // backspacing
                     val len = DEL_LENGTHS.random(r)
                     assertReplace(c - len, c, "", sb, gb)
                     c -= len
                 }
                 3 -> { // replacing
                     val txt = INSERT_TEXTS.random(r)
                     val len = DEL_LENGTHS.random(r)

                     assertReplace(c, c + len, txt, sb, gb)
                 }
             }
         }
     }
 }
	/*
	* Copyright 2019 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	package androidx.ui.input

	import androidx.test.filters.SmallTest
	import androidx.ui.text.InternalTextApi
	import org.junit.Assert.assertEquals
	import org.junit.Test
	import org.junit.runner.RunWith
	import org.junit.runners.JUnit4
	import kotlin.random.Random

	@OptIn(InternalTextApi::class)
	@SmallTest
	@RunWith(JUnit4::class)
	class GapBufferTest {

	private fun assertStrWithChars(expected: String, pgb: PartialGapBuffer) {
	assertEquals(expected, pgb.toString())
	for (i in 0 until expected.length) {
	assertEquals(expected[i], pgb[i])
	}
	}

	@Test
	fun insertTest_insert_to_empty_string() {
	assertStrWithChars("A", PartialGapBuffer("").apply {
	replace(0, 0, "A")
	})
	}

	@Test
	fun insertTest_insert_and_append() {
	assertStrWithChars("BA", PartialGapBuffer("").apply {
	replace(0, 0, "A")
	replace(0, 0, "B")
	})
	}

	@Test
	fun insertTest_insert_and_prepend() {
	assertStrWithChars("AB", PartialGapBuffer("").apply {
	replace(0, 0, "A")
	replace(1, 1, "B")
	})
	}

	@Test
	fun insertTest_insert_and_insert_into_middle() {
	assertStrWithChars("ABA", PartialGapBuffer("").apply {
	replace(0, 0, "AA")
	replace(1, 1, "B")
	})
	}

	@Test
	fun insertTest_intoExistingText_prepend() {
	assertStrWithChars("AXX", PartialGapBuffer("XX").apply {
	replace(0, 0, "A")
	})
	}

	@Test
	fun insertTest_intoExistingText_insert_into_middle() {
	assertStrWithChars("XAX", PartialGapBuffer("XX").apply {
	replace(1, 1, "A")
	})
	}

	@Test
	fun insertTest_intoExistingText_append() {
	assertStrWithChars("XXA", PartialGapBuffer("XX").apply {
	replace(2, 2, "A")
	})
	}

	@Test
	fun insertTest_intoExistingText_prepend_and_prepend() {
	assertStrWithChars("BAXX", PartialGapBuffer("XX").apply {
	replace(0, 0, "A")
	replace(0, 0, "B")
	})
	}

	@Test
	fun insertTest_intoExistingText_prepend_and_append() {
	assertStrWithChars("ABXX", PartialGapBuffer("XX").apply {
	replace(0, 0, "A")
	replace(1, 1, "B")
	})
	}

	@Test
	fun insertTest_intoExistingText_prepend_and_insert_middle() {
	assertStrWithChars("AXBX", PartialGapBuffer("XX").apply {
	replace(0, 0, "A")
	replace(2, 2, "B")
	})
	}

	@Test
	fun insertTest_intoExistingText_insert_two_chars_and_append() {
	assertStrWithChars("ABAXX", PartialGapBuffer("XX").apply {
	replace(0, 0, "AA")
	replace(1, 1, "B")
	})
	}

	@Test
	fun deleteTest_insert_and_delete_from_head() {
	assertStrWithChars("BC", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(0, 1, "")
	})
	}

	@Test
	fun deleteTest_insert_and_delete_middle() {
	assertStrWithChars("AC", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(1, 2, "")
	})
	}

	@Test
	fun deleteTest_insert_and_delete_tail() {
	assertStrWithChars("AB", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(2, 3, "")
	})
	}

	@Test
	fun deleteTest_insert_and_delete_two_head() {
	assertStrWithChars("C", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(0, 2, "")
	})
	}

	@Test
	fun deleteTest_insert_and_delete_two_tail() {
	assertStrWithChars("A", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(1, 3, "")
	})
	}

	@Test
	fun deleteTest_insert_and_delete_with_two_instruction_from_haed() {
	assertStrWithChars("C", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(0, 1, "")
	replace(0, 1, "")
	})
	}

	@Test
	fun deleteTest_insert_and_delet_with_two_instruction_from_head_and_tail() {
	assertStrWithChars("B", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(0, 1, "")
	replace(1, 2, "")
	})
	}

	@Test
	fun deleteTest_insert_and_delet_with_two_instruction_from_tail() {
	assertStrWithChars("A", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(1, 2, "")
	replace(1, 2, "")
	})
	}

	@Test
	fun deleteTest_insert_and_delete_three_chars() {
	assertStrWithChars("", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(0, 3, "")
	})
	}

	@Test
	fun deleteTest_insert_and_delete_three_chars_with_three_instructions() {
	assertStrWithChars("", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(0, 1, "")
	replace(0, 1, "")
	replace(0, 1, "")
	})
	}

	@Test
	fun deleteTest_fromExistingText_from_head() {
	assertStrWithChars("BC", PartialGapBuffer("ABC").apply {
	replace(0, 1, "")
	})
	}

	@Test
	fun deleteTest_fromExistingText_from_middle() {
	assertStrWithChars("AC", PartialGapBuffer("ABC").apply {
	replace(1, 2, "")
	})
	}

	@Test
	fun deleteTest_fromExistingText_from_tail() {
	assertStrWithChars("AB", PartialGapBuffer("ABC").apply {
	replace(2, 3, "")
	})
	}

	@Test
	fun deleteTest_fromExistingText_delete_two_chars_from_head() {
	assertStrWithChars("C", PartialGapBuffer("ABC").apply {
	replace(0, 2, "")
	})
	}

	@Test
	fun deleteTest_fromExistingText_delete_two_chars_from_tail() {
	assertStrWithChars("A", PartialGapBuffer("ABC").apply {
	replace(1, 3, "")
	})
	}

	@Test
	fun deleteTest_fromExistingText_delete_two_chars_with_two_instruction_from_head() {
	assertStrWithChars("C", PartialGapBuffer("ABC").apply {
	replace(0, 1, "")
	replace(0, 1, "")
	})
	}

	@Test
	fun deleteTest_fromExistingText_delete_two_chars_with_two_instruction_from_head_and_tail() {
	assertStrWithChars("B", PartialGapBuffer("ABC").apply {
	replace(0, 1, "")
	replace(1, 2, "")
	})
	}

	@Test
	fun deleteTest_fromExistingText_delete_two_chars_with_two_instruction_from_tail() {
	assertStrWithChars("A", PartialGapBuffer("ABC").apply {
	replace(1, 2, "")
	replace(1, 2, "")
	})
	}

	@Test
	fun deleteTest_fromExistingText_delete_three_chars() {
	assertStrWithChars("", PartialGapBuffer("ABC").apply {
	replace(0, 3, "")
	})
	}

	@Test
	fun deleteTest_fromExistingText_delete_three_chars_with_three_instructions() {
	assertStrWithChars("", PartialGapBuffer("ABC").apply {
	replace(0, 1, "")
	replace(0, 1, "")
	replace(0, 1, "")
	})
	}

	@Test
	fun replaceTest_head() {
	assertStrWithChars("XBC", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(0, 1, "X")
	})
	}

	@Test
	fun replaceTest_middle() {
	assertStrWithChars("AXC", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(1, 2, "X")
	})
	}

	@Test
	fun replaceTest_tail() {
	assertStrWithChars("ABX", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(2, 3, "X")
	})
	}

	@Test
	fun replaceTest_head_two_chars() {
	assertStrWithChars("XC", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(0, 2, "X")
	})
	}

	@Test
	fun replaceTest_middle_two_chars() {
	assertStrWithChars("AX", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(1, 3, "X")
	})
	}

	@Test
	fun replaceTest_three_chars() {
	assertStrWithChars("X", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(0, 3, "X")
	})
	}

	@Test
	fun replaceTest_one_char_with_two_chars_from_head() {
	assertStrWithChars("XYBC", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(0, 1, "XY")
	})
	}

	@Test
	fun replaceTest_one_char_with_two_chars_from_middle() {
	assertStrWithChars("AXYC", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(1, 2, "XY")
	})
	}

	@Test
	fun replaceTest_one_char_with_two_chars_from_tail() {
	assertStrWithChars("ABXY", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(2, 3, "XY")
	})
	}

	@Test
	fun replaceTest_two_chars_with_two_chars_from_head() {
	assertStrWithChars("XYC", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(0, 2, "XY")
	})
	}

	@Test
	fun replaceTest_two_chars_with_two_chars_from_tail() {
	assertStrWithChars("AXY", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(1, 3, "XY")
	})
	}

	@Test
	fun replaceTest_three_chars_with_two_char() {
	assertStrWithChars("XY", PartialGapBuffer("").apply {
	replace(0, 0, "ABC")
	replace(0, 3, "XY")
	})
	}

	@Test
	fun replaceTest_fromExistingText_head() {
	assertStrWithChars("XBC", PartialGapBuffer("ABC").apply {
	replace(0, 1, "X")
	})
	}

	@Test
	fun replaceTest_fromExistingText_middle() {
	assertStrWithChars("AXC", PartialGapBuffer("ABC").apply {
	replace(1, 2, "X")
	})
	}

	@Test
	fun replaceTest_fromExistingText_tail() {
	assertStrWithChars("ABX", PartialGapBuffer("ABC").apply {
	replace(2, 3, "X")
	})
	}

	@Test
	fun replaceTest_fromExistingText_two_chars_with_one_char_from_head() {
	assertStrWithChars("XC", PartialGapBuffer("ABC").apply {
	replace(0, 2, "X")
	})
	}

	@Test
	fun replaceTest_fromExistingText_two_chars_with_one_char_from_tail() {
	assertStrWithChars("AX", PartialGapBuffer("ABC").apply {
	replace(1, 3, "X")
	})
	}

	@Test
	fun replaceTest_fromExistingText_three_chars() {
	assertStrWithChars("X", PartialGapBuffer("ABC").apply {
	replace(0, 3, "X")
	})
	}

	@Test
	fun replaceTest_fromExistingText_one_char_with_two_chars_from_head() {
	assertStrWithChars("XYBC", PartialGapBuffer("ABC").apply {
	replace(0, 1, "XY")
	})
	}

	@Test
	fun replaceTest_fromExistingText_one_char_with_two_chars_from_middle() {
	assertStrWithChars("AXYC", PartialGapBuffer("ABC").apply {
	replace(1, 2, "XY")
	})
	}

	@Test
	fun replaceTest_fromExistingText_one_char_with_two_chars_from_tail() {
	assertStrWithChars("ABXY", PartialGapBuffer("ABC").apply {
	replace(2, 3, "XY")
	})
	}

	@Test
	fun replaceTest_fromExistingText_two_chars_with_two_chars_from_head() {
	assertStrWithChars("XYC", PartialGapBuffer("ABC").apply {
	replace(0, 2, "XY")
	})
	}

	@Test
	fun replaceTest_fromExistingText_two_chars_with_two_chars_from_tail() {
	assertStrWithChars("AXY", PartialGapBuffer("ABC").apply {
	replace(1, 3, "XY")
	})
	}

	@Test
	fun replaceTest_fromExistingText_three_chars_with_three_chars() {
	assertStrWithChars("XY", PartialGapBuffer("ABC").apply {
	replace(0, 3, "XY")
	})
	}

	// Compare with the result of StringBuffer. We trust the StringBuffer works correctly
	private fun assertReplace(
	start: Int,
	end: Int,
	str: String,
	sb: StringBuffer,
	gb: PartialGapBuffer
	) {
	sb.replace(start, end, str)
	gb.replace(start, end, str)
	assertStrWithChars(sb.toString(), gb)
	}

	private val LONG_INIT_TEXT = "ABCDEFGHIJKLMNOPQRSTUVWXYZ".repeat(256)
	private val SHORT_TEXT = "A"
	private val MEDIUM_TEXT = "Hello, World"
	private val LONG_TEXT = "abcdefghijklmnopqrstuvwxyz".repeat(16)

	@Test
	fun longTextTest_keep_insertion() {
	val sb = StringBuffer(LONG_INIT_TEXT)
	val gb = PartialGapBuffer(LONG_INIT_TEXT)

	var c = 256 // cursor
	assertReplace(c, c, SHORT_TEXT, sb, gb)
	c += SHORT_TEXT.length
	assertReplace(c, c, MEDIUM_TEXT, sb, gb)
	c += MEDIUM_TEXT.length
	assertReplace(c, c, LONG_TEXT, sb, gb)
	c += LONG_TEXT.length
	assertReplace(c, c, MEDIUM_TEXT, sb, gb)
	c += MEDIUM_TEXT.length
	assertReplace(c, c, SHORT_TEXT, sb, gb)
	}

	@Test
	fun longTextTest_keep_deletion() {
	val sb = StringBuffer(LONG_INIT_TEXT)
	val gb = PartialGapBuffer(LONG_INIT_TEXT)

	var c = 2048 // cursor
	// Forward deletion
	assertReplace(c, c + 10, "", sb, gb)
	assertReplace(c, c + 100, "", sb, gb)
	assertReplace(c, c + 1000, "", sb, gb)

	// Backspacing
	assertReplace(c - 10, c, "", sb, gb)
	c -= 10
	assertReplace(c - 100, c, "", sb, gb)
	c -= 100
	assertReplace(c - 1000, c, "", sb, gb)
	}

	@Test
	fun longTextTest_farInput() {
	val sb = StringBuffer(LONG_INIT_TEXT)
	val gb = PartialGapBuffer(LONG_INIT_TEXT)

	assertReplace(1024, 1024, "Hello, World", sb, gb)
	assertReplace(128, 128, LONG_TEXT, sb, gb)
	}

	@Test
	fun randomInsertDeleteStressTest() {
	val sb = StringBuffer(LONG_INIT_TEXT)
	val gb = PartialGapBuffer(LONG_INIT_TEXT)

	val r = Random(10 /* fix the seed for reproduction */)

	val INSERT_TEXTS = arrayOf(SHORT_TEXT, MEDIUM_TEXT, LONG_TEXT)
	val DEL_LENGTHS = arrayOf(1, 10, 100)

	var c = LONG_INIT_TEXT.length / 2

	for (i in 0..100) {
	when (r.nextInt() % 4) {
	0 -> { // insert
	val txt = INSERT_TEXTS.random(r)
	assertReplace(c, c, txt, sb, gb)
	c += txt.length
	}
	1 -> { // forward delete
	assertReplace(c, c + DEL_LENGTHS.random(r), "", sb, gb)
	}
	2 -> { // backspacing
	val len = DEL_LENGTHS.random(r)
	assertReplace(c - len, c, "", sb, gb)
	c -= len
	}
	3 -> { // replacing
	val txt = INSERT_TEXTS.random(r)
	val len = DEL_LENGTHS.random(r)

	assertReplace(c, c + len, txt, sb, gb)
	}
	}
	}
	}
	}