Add requirement that incrementBy be perfectly divisible into Number.MIN_VALUE

Author: 05nelsonm

library/bits/src/commonMain/kotlin/org/kotlincrypto/bitops/bits/Counter.kt

@@ -93,12 +93,14 @@ public sealed class Counter private constructor() {
          *  - [incrementBy] is less than or equal to 0
          *  - [incrementBy] is greater than [MAX_INCREMENT]
          *  - [incrementBy] is not a factor of 8
+         *  - [incrementBy] does not go into [Int.MIN_VALUE] (i.e. when `Int.MIN_VALUE % incrementBy != 0`)
          *  - [lo] is not a factor of [incrementBy]
          * */
         public constructor(lo: Int, hi: Int, incrementBy: Int): super() {
             require(incrementBy > 0) { "incrementBy[$incrementBy] must be greater than 0" }
             require(incrementBy <= MAX_INCREMENT) { "incrementBy[$incrementBy] must be less than or equal to $MAX_INCREMENT" }
             require(incrementBy % 8 == 0) { "incrementBy[$incrementBy] must be a factor of 8" }
+            require(Int.MIN_VALUE % incrementBy == 0) { "Long.MIN_VALUE % incrementBy[$incrementBy] != 0" }
             require(lo % incrementBy == 0) { "lo must be a factor of incrementBy[$incrementBy]" }
 
             this.incrementBy = incrementBy
@@ -210,12 +212,14 @@ public sealed class Counter private constructor() {
          *  - [incrementBy] is less than or equal to 0
          *  - [incrementBy] is greater than [MAX_INCREMENT]
          *  - [incrementBy] is not a factor of 8
+         *  - [incrementBy] does not go into [Long.MIN_VALUE] (i.e. when `Long.MIN_VALUE % incrementBy != 0`)
          *  - [lo] is not a factor of [incrementBy]
          * */
         public constructor(lo: Long, hi: Long, incrementBy: Long): super() {
             require(incrementBy > 0L) { "incrementBy[$incrementBy] must be greater than 0" }
             require(incrementBy <= MAX_INCREMENT) { "incrementBy[$incrementBy] must be less than or equal to $MAX_INCREMENT" }
             require(incrementBy % 8 == 0L) { "incrementBy[$incrementBy] must be a factor of 8" }
+            require(Long.MIN_VALUE % incrementBy == 0L) { "Long.MIN_VALUE % incrementBy[$incrementBy] != 0" }
             require(lo % incrementBy == 0L) { "lo must be a factor of incrementBy[$incrementBy]" }
 
             this.incrementBy = incrementBy

library/bits/src/commonTest/kotlin/org/kotlincrypto/bitops/bits/CounterUnitTest.kt

@@ -52,17 +52,27 @@ class CounterUnitTest {
         }
     }
 
+    @Test
+    fun givenIncrementBy_whenNumberMinNotDivisibleByIt_thenThrowsException() {
+        assertFailsWith<IllegalArgumentException> {
+            Counter.Bit32(0, 0, 24)
+        }
+        assertFailsWith<IllegalArgumentException> {
+            Counter.Bit64(0, 0, 24)
+        }
+    }
+
     @Test
     fun givenLo_whenNotFactoryIncrementBy_thenThrowsException() {
-        // Would throw if 24 was not a factor of 8...
-        Counter.Bit32(24)
-        Counter.Bit64(24)
+        // Would throw if 32 was not a factor of 8...
+        Counter.Bit32(32)
+        Counter.Bit64(32)
 
         assertFailsWith<IllegalArgumentException> {
-            Counter.Bit32(8, 0, 24)
+            Counter.Bit32(8, 0, 32)
         }
         assertFailsWith<IllegalArgumentException> {
-            Counter.Bit64(16, 0, 24)
+            Counter.Bit64(16, 0, 32)
         }
     }