Implement toString() in RetryPolicy and RetryExecution implementations

Closes gh-35029

spring-core/src/main/java/org/springframework/core/retry/support/MaxRetryAttemptsPolicy.java

@@ -21,10 +21,10 @@ import org.springframework.core.retry.RetryPolicy;
 import org.springframework.util.Assert;
 
 /**
- * A {@link RetryPolicy} based on a number of attempts that should not exceed a
- * configured maximum number.
+ * A {@link RetryPolicy} based on a maximum number of retry attempts.
  *
  * @author Mahmoud Ben Hassine
+ * @author Sam Brannen
  * @since 7.0
  */
 public class MaxRetryAttemptsPolicy implements RetryPolicy {
@@ -56,11 +56,6 @@ public class MaxRetryAttemptsPolicy implements RetryPolicy {
 		setMaxRetryAttempts(maxRetryAttempts);
 	}
 
-	@Override
-	public RetryExecution start() {
-		return new MaxRetryAttemptsPolicyExecution();
-	}
-
 	/**
 	 * Set the maximum number of retry attempts.
 	 * @param maxRetryAttempts the maximum number of retry attempts; must be greater
@@ -71,6 +66,16 @@ public class MaxRetryAttemptsPolicy implements RetryPolicy {
 		this.maxRetryAttempts = maxRetryAttempts;
 	}
 
+	@Override
+	public RetryExecution start() {
+		return new MaxRetryAttemptsPolicyExecution();
+	}
+
+	@Override
+	public String toString() {
+		return "MaxRetryAttemptsPolicy[maxRetryAttempts=%d]".formatted(this.maxRetryAttempts);
+	}
+
 
 	/**
 	 * A {@link RetryExecution} based on a maximum number of retry attempts.
@@ -83,6 +88,13 @@ public class MaxRetryAttemptsPolicy implements RetryPolicy {
 		public boolean shouldRetry(Throwable throwable) {
 			return (this.retryAttempts++ < MaxRetryAttemptsPolicy.this.maxRetryAttempts);
 		}
+
+		@Override
+		public String toString() {
+			return "MaxRetryAttemptsPolicyExecution[retryAttempts=%d, maxRetryAttempts=%d]"
+					.formatted(this.retryAttempts, MaxRetryAttemptsPolicy.this.maxRetryAttempts);
+		}
+
 	}
 
 }

spring-core/src/main/java/org/springframework/core/retry/support/MaxRetryDurationPolicy.java

@@ -24,9 +24,10 @@ import org.springframework.core.retry.RetryPolicy;
 import org.springframework.util.Assert;
 
 /**
- * A {@link RetryPolicy} based on a maximum retry duration.
+ * A {@link RetryPolicy} based on a maximum retry {@link Duration}.
  *
  * @author Mahmoud Ben Hassine
+ * @author Sam Brannen
  * @since 7.0
  */
 public class MaxRetryDurationPolicy implements RetryPolicy {
@@ -42,7 +43,7 @@ public class MaxRetryDurationPolicy implements RetryPolicy {
 
 	/**
 	 * Create a new {@code MaxRetryDurationPolicy} with the default maximum retry
-	 * duration.
+	 * {@link Duration}.
 	 * @see #DEFAULT_MAX_RETRY_DURATION
 	 */
 	public MaxRetryDurationPolicy() {
@@ -50,20 +51,15 @@ public class MaxRetryDurationPolicy implements RetryPolicy {
 
 	/**
 	 * Create a new {@code MaxRetryDurationPolicy} with the specified maximum retry
-	 * duration.
+	 * {@link Duration}.
 	 * @param maxRetryDuration the maximum retry duration; must be positive
 	 */
 	public MaxRetryDurationPolicy(Duration maxRetryDuration) {
 		setMaxRetryDuration(maxRetryDuration);
 	}
 
-	@Override
-	public RetryExecution start() {
-		return new MaxRetryDurationPolicyExecution();
-	}
-
 	/**
-	 * Set the maximum retry duration.
+	 * Set the maximum retry {@link Duration}.
 	 * @param maxRetryDuration the maximum retry duration; must be positive
 	 */
 	public void setMaxRetryDuration(Duration maxRetryDuration) {
@@ -72,6 +68,17 @@ public class MaxRetryDurationPolicy implements RetryPolicy {
 		this.maxRetryDuration = maxRetryDuration;
 	}
 
+	@Override
+	public RetryExecution start() {
+		return new MaxRetryDurationPolicyExecution();
+	}
+
+	@Override
+	public String toString() {
+		return "MaxRetryDurationPolicy[maxRetryDuration=%dms]".formatted(this.maxRetryDuration.toMillis());
+	}
+
+
 	/**
 	 * A {@link RetryExecution} based on a maximum retry duration.
 	 */
@@ -84,6 +91,13 @@ public class MaxRetryDurationPolicy implements RetryPolicy {
 			Duration currentRetryDuration = Duration.between(this.retryStartTime, LocalDateTime.now());
 			return currentRetryDuration.compareTo(MaxRetryDurationPolicy.this.maxRetryDuration) <= 0;
 		}
+
+		@Override
+		public String toString() {
+			return "MaxRetryDurationPolicyExecution[retryStartTime=%s, maxRetryDuration=%dms]"
+					.formatted(this.retryStartTime, MaxRetryDurationPolicy.this.maxRetryDuration.toMillis());
+		}
+
 	}
 
 }

spring-core/src/main/java/org/springframework/core/retry/support/PredicateRetryPolicy.java

@@ -25,6 +25,7 @@ import org.springframework.core.retry.RetryPolicy;
  * A {@link RetryPolicy} based on a {@link Predicate}.
  *
  * @author Mahmoud Ben Hassine
+ * @author Sam Brannen
  * @since 7.0
  */
 public class PredicateRetryPolicy implements RetryPolicy {
@@ -44,7 +45,31 @@ public class PredicateRetryPolicy implements RetryPolicy {
 
 	@Override
 	public RetryExecution start() {
-		return this.predicate::test;
+		return new PredicateRetryPolicyExecution();
+	}
+
+	@Override
+	public String toString() {
+		return "PredicateRetryPolicy[predicate=%s]".formatted(this.predicate.getClass().getSimpleName());
+	}
+
+
+	/**
+	 * A {@link RetryExecution} based on a {@link Predicate}.
+	 */
+	private class PredicateRetryPolicyExecution implements RetryExecution {
+
+		@Override
+		public boolean shouldRetry(Throwable throwable) {
+			return PredicateRetryPolicy.this.predicate.test(throwable);
+		}
+
+		@Override
+		public String toString() {
+			return "PredicateRetryPolicyExecution[predicate=%s]"
+					.formatted(PredicateRetryPolicy.this.predicate.getClass().getSimpleName());
+		}
+
 	}
 
 }

spring-core/src/test/java/org/springframework/core/retry/support/MaxRetryAttemptsPolicyTests.java

@@ -25,9 +25,11 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
 import static org.mockito.Mockito.mock;
 
 /**
- * Tests for {@link MaxRetryAttemptsPolicy}.
+ * Tests for {@link MaxRetryAttemptsPolicy} and its {@link RetryExecution}.
  *
  * @author Mahmoud Ben Hassine
+ * @author Sam Brannen
+ * @since 7.0
  */
 class MaxRetryAttemptsPolicyTests {
 
@@ -44,14 +46,69 @@ class MaxRetryAttemptsPolicyTests {
 		assertThat(retryExecution.shouldRetry(throwable)).isTrue();
 		assertThat(retryExecution.shouldRetry(throwable)).isTrue();
 		assertThat(retryExecution.shouldRetry(throwable)).isTrue();
+
+		assertThat(retryExecution.shouldRetry(throwable)).isFalse();
+		assertThat(retryExecution.shouldRetry(throwable)).isFalse();
+	}
+
+	@Test
+	void customMaxRetryAttempts() {
+		// given
+		MaxRetryAttemptsPolicy retryPolicy = new MaxRetryAttemptsPolicy(2);
+		Throwable throwable = mock();
+
+		// when
+		RetryExecution retryExecution = retryPolicy.start();
+
+		// then
+		assertThat(retryExecution.shouldRetry(throwable)).isTrue();
+		assertThat(retryExecution.shouldRetry(throwable)).isTrue();
+
+		assertThat(retryExecution.shouldRetry(throwable)).isFalse();
 		assertThat(retryExecution.shouldRetry(throwable)).isFalse();
 	}
 
 	@Test
 	void invalidMaxRetryAttempts() {
+		assertThatIllegalArgumentException()
+				.isThrownBy(() -> new MaxRetryAttemptsPolicy(0))
+				.withMessage("Max retry attempts must be greater than zero");
 		assertThatIllegalArgumentException()
 				.isThrownBy(() -> new MaxRetryAttemptsPolicy(-1))
 				.withMessage("Max retry attempts must be greater than zero");
 	}
 
+	@Test
+	void toStringImplementations() {
+		MaxRetryAttemptsPolicy policy1 = new MaxRetryAttemptsPolicy();
+		MaxRetryAttemptsPolicy policy2 = new MaxRetryAttemptsPolicy(1);
+
+		assertThat(policy1).asString().isEqualTo("MaxRetryAttemptsPolicy[maxRetryAttempts=3]");
+		assertThat(policy2).asString().isEqualTo("MaxRetryAttemptsPolicy[maxRetryAttempts=1]");
+
+		RetryExecution retryExecution = policy1.start();
+		assertThat(retryExecution).asString()
+				.isEqualTo("MaxRetryAttemptsPolicyExecution[retryAttempts=0, maxRetryAttempts=3]");
+
+		assertThat(retryExecution.shouldRetry(mock())).isTrue();
+		assertThat(retryExecution).asString()
+				.isEqualTo("MaxRetryAttemptsPolicyExecution[retryAttempts=1, maxRetryAttempts=3]");
+
+		assertThat(retryExecution.shouldRetry(mock())).isTrue();
+		assertThat(retryExecution).asString()
+				.isEqualTo("MaxRetryAttemptsPolicyExecution[retryAttempts=2, maxRetryAttempts=3]");
+
+		assertThat(retryExecution.shouldRetry(mock())).isTrue();
+		assertThat(retryExecution).asString()
+				.isEqualTo("MaxRetryAttemptsPolicyExecution[retryAttempts=3, maxRetryAttempts=3]");
+
+		assertThat(retryExecution.shouldRetry(mock())).isFalse();
+		assertThat(retryExecution).asString()
+				.isEqualTo("MaxRetryAttemptsPolicyExecution[retryAttempts=4, maxRetryAttempts=3]");
+
+		assertThat(retryExecution.shouldRetry(mock())).isFalse();
+		assertThat(retryExecution).asString()
+				.isEqualTo("MaxRetryAttemptsPolicyExecution[retryAttempts=5, maxRetryAttempts=3]");
+	}
+
 }

spring-core/src/test/java/org/springframework/core/retry/support/MaxRetryDurationPolicyTests.java

@@ -20,12 +20,17 @@ import java.time.Duration;
 
 import org.junit.jupiter.api.Test;
 
+import org.springframework.core.retry.RetryExecution;
+
+import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 
 /**
- * Tests for {@link MaxRetryDurationPolicy}.
+ * Tests for {@link MaxRetryDurationPolicy} and its {@link RetryExecution}.
  *
  * @author Mahmoud Ben Hassine
+ * @author Sam Brannen
+ * @since 7.0
  */
 class MaxRetryDurationPolicyTests {
 
@@ -36,4 +41,18 @@ class MaxRetryDurationPolicyTests {
 				.withMessage("Max retry duration must be positive");
 	}
 
+	@Test
+	void toStringImplementations() {
+		MaxRetryDurationPolicy policy1 = new MaxRetryDurationPolicy();
+		MaxRetryDurationPolicy policy2 = new MaxRetryDurationPolicy(Duration.ofSeconds(1));
+
+		assertThat(policy1).asString().isEqualTo("MaxRetryDurationPolicy[maxRetryDuration=3000ms]");
+		assertThat(policy2).asString().isEqualTo("MaxRetryDurationPolicy[maxRetryDuration=1000ms]");
+
+		assertThat(policy1.start()).asString()
+				.matches("MaxRetryDurationPolicyExecution\\[retryStartTime=.+, maxRetryDuration=3000ms\\]");
+		assertThat(policy2.start()).asString()
+				.matches("MaxRetryDurationPolicyExecution\\[retryStartTime=.+, maxRetryDuration=1000ms\\]");
+	}
+
 }

spring-core/src/test/java/org/springframework/core/retry/support/PredicateRetryPolicyTests.java

@@ -25,28 +25,46 @@ import org.springframework.core.retry.RetryExecution;
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
- * Tests for {@link PredicateRetryPolicy}.
+ * Tests for {@link PredicateRetryPolicy} and its {@link RetryExecution}.
  *
  * @author Mahmoud Ben Hassine
+ * @author Sam Brannen
+ * @since 7.0
  */
 class PredicateRetryPolicyTests {
 
 	@Test
 	void predicateRetryPolicy() {
-		// given
-		class MyException extends Exception {
-			@java.io.Serial
-			private static final long serialVersionUID = 1L;
-		}
-		Predicate<Throwable> predicate = MyException.class::isInstance;
+		Predicate<Throwable> predicate = NumberFormatException.class::isInstance;
 		PredicateRetryPolicy retryPolicy = new PredicateRetryPolicy(predicate);
 
-		// when
 		RetryExecution retryExecution = retryPolicy.start();
 
-		// then
-		assertThat(retryExecution.shouldRetry(new MyException())).isTrue();
+		assertThat(retryExecution.shouldRetry(new NumberFormatException())).isTrue();
 		assertThat(retryExecution.shouldRetry(new IllegalStateException())).isFalse();
 	}
 
+	@Test
+	void toStringImplementations() {
+		PredicateRetryPolicy policy1 = new PredicateRetryPolicy(NumberFormatException.class::isInstance);
+		PredicateRetryPolicy policy2 = new PredicateRetryPolicy(new NumberFormatExceptionMatcher());
+
+		assertThat(policy1).asString().matches("PredicateRetryPolicy\\[predicate=PredicateRetryPolicyTests.+?Lambda.+?\\]");
+		assertThat(policy2).asString().isEqualTo("PredicateRetryPolicy[predicate=NumberFormatExceptionMatcher]");
+
+		assertThat(policy1.start()).asString()
+				.matches("PredicateRetryPolicyExecution\\[predicate=PredicateRetryPolicyTests.+?Lambda.+?\\]");
+		assertThat(policy2.start()).asString()
+				.isEqualTo("PredicateRetryPolicyExecution[predicate=NumberFormatExceptionMatcher]");
+	}
+
+
+	private static class NumberFormatExceptionMatcher implements Predicate<Throwable> {
+
+		@Override
+		public boolean test(Throwable throwable) {
+			return (throwable instanceof NumberFormatException);
+		}
+	}
+
 }