Enable assertions to be made on LoggingEvents from any thread.

src/main/java/com/github/valfirst/slf4jtest/AbstractTestLoggerAssert.java

@@ -1,19 +1,24 @@
 package com.github.valfirst.slf4jtest;
 
 import java.util.Arrays;
+import java.util.List;
 import java.util.Optional;
 import java.util.function.Predicate;
+import java.util.function.Supplier;
 import org.assertj.core.api.AbstractAssert;
 import uk.org.lidalia.slf4jext.Level;
 
 abstract class AbstractTestLoggerAssert<C extends AbstractAssert<C, TestLogger>>
         extends AbstractAssert<C, TestLogger> {
+    protected Supplier<List<LoggingEvent>> loggingEventsSupplier;
+
     protected AbstractTestLoggerAssert(TestLogger testLogger, Class clazz) {
         super(testLogger, clazz);
+        loggingEventsSupplier = testLogger::getLoggingEvents;
     }
 
     protected long getLogCount(Level level, Predicate<LoggingEvent> predicate) {
-        return actual.getLoggingEvents().stream()
+        return loggingEventsSupplier.get().stream()
                 .filter(event -> level.equals(event.getLevel()) && predicate.test(event))
                 .count();
     }

src/main/java/com/github/valfirst/slf4jtest/TestLoggerAssert.java

@@ -5,14 +5,27 @@
 /**
 * A set of assertions to validate that logs have been logged to a {@link TestLogger}.
 *
-* <p>Should be thread safe, as this uses <code>testLogger.getLoggingEvents()</code>.
+* <p>Should be thread safe, as this uses <code>testLogger.getLoggingEvents()</code> by default. The
+* assertion mode can be switched to use <code>testLogger.getAllLoggingEvents()</code> by calling
+* {@link #anyThread()}.
 */
 public class TestLoggerAssert extends AbstractTestLoggerAssert<TestLoggerAssert> {
 
     protected TestLoggerAssert(TestLogger testLogger) {
         super(testLogger, TestLoggerAssert.class);
     }
 
+    /**
+    * Changes the assertion mode to verify that log messages have been logged regardless of which
+    * thread actually logged the message.
+    *
+    * @return a {@link TestLoggerAssert} for chaining
+    */
+    public TestLoggerAssert anyThread() {
+        loggingEventsSupplier = actual::getAllLoggingEvents;
+        return this;
+    }
+
     /**
     * Verify that a log message, at a specific level, has been logged by the test logger.
     *
@@ -47,7 +60,7 @@ public TestLoggerAssert hasLogged(
     * @return a {@link TestLoggerAssert} for chaining
     */
     public TestLoggerAssert hasLogged(LoggingEvent event) {
-        if (!actual.getLoggingEvents().contains(event)) {
+        if (!loggingEventsSupplier.get().contains(event)) {
             failWithMessage("Failed to find %s", event);
         }
         return this;
@@ -87,7 +100,7 @@ public TestLoggerAssert hasNotLogged(
     * @return a {@link TestLoggerAssert} for chaining
     */
     public TestLoggerAssert hasNotLogged(LoggingEvent event) {
-        if (actual.getLoggingEvents().contains(event)) {
+        if (loggingEventsSupplier.get().contains(event)) {
             failWithMessage("Found %s, even though we expected not to", event);
         }
         return this;
@@ -100,6 +113,8 @@ public TestLoggerAssert hasNotLogged(LoggingEvent event) {
     * @return the {@link LevelAssert} bound to the given {@link Level}
     */
     public LevelAssert hasLevel(Level level) {
-        return new LevelAssert(actual, level);
+        LevelAssert levelAssert = new LevelAssert(actual, level);
+        levelAssert.loggingEventsSupplier = loggingEventsSupplier;
+        return levelAssert;
     }
 }