Check if exponent is less than zero or if the divisor is larger than …

…divisor, fixes #195
ionspin · Dec 1, 2021 · 3aa137f · 3aa137f
1 parent d39c8dd
commit 3aa137f
Show file tree

Hide file tree

Showing 3 changed files with 60 additions and 1 deletion.
diff --git a/bignum/build.gradle.kts b/bignum/build.gradle.kts
@@ -448,6 +448,7 @@ tasks {
         val jvmTest by getting(Test::class) {
             testLogging {
                 events("PASSED", "FAILED", "SKIPPED")
+                exceptionFormat = org.gradle.api.tasks.testing.logging.TestExceptionFormat.FULL
             }
         }
 

diff --git a/bignum/src/commonMain/kotlin/com/ionspin/kotlin/bignum/decimal/BigDecimal.kt b/bignum/src/commonMain/kotlin/com/ionspin/kotlin/bignum/decimal/BigDecimal.kt
@@ -1328,9 +1328,15 @@ class BigDecimal private constructor(
 
     /**
      * Quotient and remainder of **integer** division on this bigDecimal. If there is no rounding mode defined in decimal mode
-     * #RoundingMode.FLOOR will be used
+     * #RoundingMode.FLOOR will be used. Uses truncating division to determine quotient, which means that the sign of remainder will be same as sign of dividend
      */
     override fun divideAndRemainder(other: BigDecimal): Pair<BigDecimal, BigDecimal> {
+        if (exponent < 0) {
+            return Pair(ZERO, this)
+        }
+        if (other.abs() > this.abs()) {
+            return Pair(ZERO, this)
+        }
         val resolvedRoundingMode = this.decimalMode ?: DecimalMode(exponent + 1, RoundingMode.FLOOR)
         val quotient = divide(other, resolvedRoundingMode)
         val quotientInfinitePrecision = quotient.copy(decimalMode = DecimalMode.DEFAULT)

diff --git a/bignum/src/commonTest/kotlin/com/ionspin/kotlin/bignum/decimal/BigDecimalDivisionTest.kt b/bignum/src/commonTest/kotlin/com/ionspin/kotlin/bignum/decimal/BigDecimalDivisionTest.kt
@@ -1,6 +1,7 @@
 package com.ionspin.kotlin.bignum.decimal
 
 import kotlin.test.Test
+import kotlin.test.assertEquals
 import kotlin.test.assertFailsWith
 import kotlin.test.assertTrue
 
@@ -105,4 +106,55 @@ class BigDecimalDivisionTest {
             val result = a / b
         }
     }
+
+    @Test
+    fun testDivideAndRemainder() {
+        run {
+            val a = 0.14.toBigDecimal()
+            val b = BigDecimal.ONE
+            val (quotient, remainder) = a.divideAndRemainder(b)
+            assertEquals(BigDecimal.ZERO, quotient)
+            assertEquals(a, remainder)
+        }
+
+        run {
+            val a = 1.14.toBigDecimal()
+            val b = BigDecimal.ONE
+            val (quotient, remainder) = a.divideAndRemainder(b)
+            assertEquals(BigDecimal.ONE, quotient)
+            assertEquals(0.14.toBigDecimal(), remainder)
+        }
+
+        run {
+            val a = 1.toBigDecimal()
+            val b = BigDecimal.ONE
+            val (quotient, remainder) = a.divideAndRemainder(b)
+            assertEquals(BigDecimal.ONE, quotient)
+            assertEquals(BigDecimal.ZERO, remainder)
+        }
+
+        run {
+            val a = 1.toBigDecimal()
+            val b = BigDecimal.TWO
+            val (quotient, remainder) = a.divideAndRemainder(b)
+            assertEquals(BigDecimal.ZERO, quotient)
+            assertEquals(BigDecimal.ONE, remainder)
+        }
+
+        run {
+            val a = 1.toBigDecimal()
+            val b = BigDecimal.TWO.negate()
+            val (quotient, remainder) = a.divideAndRemainder(b)
+            assertEquals(BigDecimal.ZERO, quotient)
+            assertEquals(BigDecimal.ONE, remainder)
+        }
+
+        run {
+            val a = -1.toBigDecimal()
+            val b = BigDecimal.TWO.negate()
+            val (quotient, remainder) = a.divideAndRemainder(b)
+            assertEquals(BigDecimal.ZERO, quotient)
+            assertEquals(BigDecimal.ONE.negate(), remainder)
+        }
+    }
 }