Add validation tests for iterationTime and iterationTimeUnit config options

Author: Abduqodiri Qurbonzoda

integration/src/test/kotlin/kotlinx/benchmark/integration/OptionsValidationTest.kt

@@ -59,11 +59,18 @@ class OptionsValidationTest : GradleTest() {
                 iterationTime = 0
                 iterationTimeUnit = "ms"
             }
+            configuration("missingIterationTimeUnit") {
+                iterations = 1
+                iterationTime = 1
+            }
         }
 
         runner.runAndFail("zeroIterationTimeBenchmark") {
             assertOutputContains("Invalid iterationTime: '0'. Expected a positive number (e.g., iterationTime = 300).")
         }
+        runner.runAndFail("missingIterationTimeUnitBenchmark") {
+            assertOutputContains("Missing iterationTimeUnit. Please provide iterationTimeUnit when specifying iterationTime.")
+        }
     }
 
     @Test
@@ -79,6 +86,10 @@ class OptionsValidationTest : GradleTest() {
                 iterationTime = 1
                 iterationTimeUnit = "seconds"
             }
+            configuration("missingIterationTime") {
+                iterations = 1
+                iterationTimeUnit = "s"
+            }
         }
 
         runner.runAndFail("invalidIterationTimeUnitBenchmark") {
@@ -87,6 +98,9 @@ class OptionsValidationTest : GradleTest() {
         runner.runAndFail("incorrectCaseIterationTimeUnitBenchmark") {
             assertOutputContains("Invalid iterationTimeUnit: 'seconds'. Accepted units: ${ValidOptions.timeUnits.joinToString(", ")} (e.g., iterationTimeUnit = \"ms\").")
         }
+        runner.runAndFail("missingIterationTimeBenchmark") {
+            assertOutputContains("Missing iterationTime. Please provide iterationTime when specifying iterationTimeUnit.")
+        }
     }
 
     @Test