Fix bug with overflow checking in Combinations

UnitTestBot · Jul 28, 2022 · 3351aaa · 3351aaa
1 parent d21426f
commit 3351aaa
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Showing 3 changed files with 20 additions and 7 deletions.
diff --git a/utbot-fuzzers/src/main/kotlin/org/utbot/fuzzer/Combinations.kt b/utbot-fuzzers/src/main/kotlin/org/utbot/fuzzer/Combinations.kt
@@ -74,9 +74,10 @@ class Combinations(vararg elementNumbers: Int): Iterable<IntArray> {
         }
         count = LongArray(elementNumbers.size) { elementNumbers[it].toLong() }
         for (i in count.size - 2 downTo 0) {
-            count[i] = count[i] * count[i + 1]
-            if(count[i] < count[i + 1]) {
-                throw TooManyCombinationsException("Long overflow or bad sequence: ${count[i]} < ${count[i + 1]}")
+            try {
+                count[i] = StrictMath.multiplyExact(count[i], count[i + 1])
+            } catch (e: ArithmeticException) {
+                throw TooManyCombinationsException("Long overflow: ${count[i]} * ${count[i + 1]}")
             }
         }
     }

diff --git a/utbot-fuzzers/src/test/kotlin/org/utbot/framework/plugin/api/CombinationsTest.kt b/utbot-fuzzers/src/test/kotlin/org/utbot/framework/plugin/api/CombinationsTest.kt
@@ -228,12 +228,24 @@ class CombinationsTest {
         assertTrue(expected.isEmpty())
     }
 
+    @Test
+    fun testCartesianProductDoesNotThrowsExceptionBeforeOverflow() {
+        // We assume that a standard method has no more than 7 parameters.
+        // In this case every parameter can accept up to 511 values without Long overflow.
+        // CartesianProduct throws exception
+        val values = Array(511) { it }.toList()
+        val parameters = Array(7) { values }.toList()
+        assertDoesNotThrow {
+            CartesianProduct(parameters, Random(0)).asSequence()
+        }
+    }
+
     @Test
     fun testCartesianProductThrowsExceptionOnOverflow() {
         // We assume that a standard method has no more than 7 parameters.
-        // In this case every parameter can accept up to 1700 values without Long overflow.
+        // In this case every parameter can accept up to 511 values without Long overflow.
         // CartesianProduct throws exception
-        val values = Array(1701) { it }.toList()
+        val values = Array(512) { it }.toList()
         val parameters = Array(7) { values }.toList()
         assertThrows(TooManyCombinationsException::class.java) {
             CartesianProduct(parameters, Random(0)).asSequence()

diff --git a/utbot-fuzzers/src/test/kotlin/org/utbot/framework/plugin/api/FuzzerTest.kt b/utbot-fuzzers/src/test/kotlin/org/utbot/framework/plugin/api/FuzzerTest.kt
@@ -115,12 +115,12 @@ class FuzzerTest {
         ), fuzz.map { arguments -> arguments.map { fuzzedValue -> fuzzedValue.model } }.toSet())
     }
 
-    // Because of Long limitation fuzzer can process no more than 1700 values for method with 7 parameters
+    // Because of Long limitation fuzzer can process no more than 511 values for method with 7 parameters
     @Test
     @Timeout(1, unit = TimeUnit.SECONDS)
     fun `the worst case works well`() {
         assertDoesNotThrow {
-            val values = (0 until 1700).map { UtPrimitiveModel(it).fuzzed() }.asSequence()
+            val values = (0 until 511).map { UtPrimitiveModel(it).fuzzed() }.asSequence()
             val provider = ModelProvider { descr ->
                 (0 until descr.parameters.size).asSequence()
                     .flatMap { index -> values.map { FuzzedParameter(index, it) } }