Add compiler contract to runRetrying

Author: michaelbull

kotlin-retry/src/commonMain/kotlin/com/github/michaelbull/retry/Retry.kt

@@ -13,7 +13,7 @@ import kotlin.coroutines.cancellation.CancellationException
 
 /**
  * Calls the specified function [block] and returns its result if invocation was successful, catching any [Throwable]
- * exception that was thrown from the [block] function executing and retrying the invocation according to
+ * exception that was thrown from the [block] function execution and retrying the invocation according to
  * [instructions][RetryInstruction] from the [policy].
  */
 public suspend inline fun <T> retry(policy: RetryPolicy<Throwable>, block: () -> T): T {

kotlin-retry/src/commonMain/kotlin/com/github/michaelbull/retry/RunRetrying.kt

@@ -2,12 +2,18 @@ package com.github.michaelbull.retry
 
 import com.github.michaelbull.retry.instruction.RetryInstruction
 import com.github.michaelbull.retry.policy.RetryPolicy
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
 
 /**
  * Calls the specified function [block] and returns its result if invocation was successful, catching any [Throwable]
- * exception that was thrown from the [block] function executing and retrying the invocation according to
+ * exception that was thrown from the [block] function execution and retrying the invocation according to
  * [instructions][RetryInstruction] from the [policy].
  */
 public suspend inline fun <T> runRetrying(policy: RetryPolicy<Throwable>, block: () -> T): T {
+    contract {
+        callsInPlace(block, InvocationKind.AT_LEAST_ONCE)
+    }
+
     return retry(policy, block)
 }

kotlin-retry/src/commonTest/kotlin/com/github/michaelbull/retry/RetryTest.kt

@@ -151,9 +151,9 @@ class RetryTest {
 
                 if (attempts == 15) {
                     cancel()
-                } else {
-                    throw AttemptsException(attempts)
                 }
+
+                throw AttemptsException(attempts)
             }
         }
 
@@ -170,7 +170,7 @@ class RetryTest {
     }
 
     @Test
-    fun cancelRetryFromWithinChildJob() = runTest {
+    fun cancelRetryWithinChildJob() = runTest {
         val every20ms = constantDelay<Throwable>(20)
         var attempts = 0