import org.junit.jupiter.api.Disabled; import org.junit.jupiter.api.DisplayName; import org.junit.jupiter.api.Test; import java.time.Duration; import java.time.Instant; import java.util.UUID; import static org.assertj.core.api.Assertions.assertThat; class RateLimiterTest { @Test @DisplayName("Allows up to window limit") void allowsUpToLimit() { TimeSource clock = new TimeSource(Instant.EPOCH); RateLimiter limiter = new RateLimiter<>(3, Duration.ofNanos(10_000L), clock); assertThat(limiter.allow("A")).isTrue(); clock.advance(Duration.ofNanos(1L)); assertThat(limiter.allow("A")).isTrue(); assertThat(limiter.allow("A")).isTrue(); assertThat(limiter.allow("A")).isFalse(); } @Disabled("Remove to run test") @Test @DisplayName("Denies requests just before boundary") void denyCloseToBoundary() { TimeSource clock = new TimeSource(Instant.EPOCH); RateLimiter limiter = new RateLimiter<>(2, Duration.ofNanos(10_000L), clock); assertThat(limiter.allow("A")).isTrue(); assertThat(limiter.allow("A")).isTrue(); assertThat(limiter.allow("A")).isFalse(); // Just before boundary: still same window clock.advance(Duration.ofNanos(9_999L)); assertThat(limiter.allow("A")).isFalse(); } @Disabled("Remove to run test") @Test @DisplayName("Allows first request at exact boundary") void allowsNewBoundary() { TimeSource clock = new TimeSource(Instant.EPOCH); RateLimiter limiter = new RateLimiter<>(2, Duration.ofNanos(10_000L), clock); assertThat(limiter.allow("A")).isTrue(); assertThat(limiter.allow("A")).isTrue(); assertThat(limiter.allow("A")).isFalse(); // At exact boundary: new window clock.advance(Duration.ofNanos(10_000L)); assertThat(limiter.allow("A")).isTrue(); } @Disabled("Remove to run test") @Test @DisplayName("Resets at boundary, then counts within window") void continuesCountingWithinWindowAfterBoundaryReset() { TimeSource clock = new TimeSource(Instant.EPOCH); RateLimiter limiter = new RateLimiter<>(2, Duration.ofNanos(5_000L), clock); assertThat(limiter.allow("key")).isTrue(); clock.advance(Duration.ofNanos(1L)); assertThat(limiter.allow("key")).isTrue(); assertThat(limiter.allow("key")).isFalse(); // Jump to next window clock.advance(Duration.ofNanos(5_000L)); assertThat(limiter.allow("key")).isTrue(); assertThat(limiter.allow("key")).isTrue(); assertThat(limiter.allow("key")).isFalse(); } @Disabled("Remove to run test") @Test @DisplayName("Independent counters/windows per key") void separateKeysHaveIndependentCountersAndWindows() { TimeSource clock = new TimeSource(Instant.EPOCH.plusNanos(42L)); RateLimiter limiter = new RateLimiter<>(1, Duration.ofNanos(100L), clock); assertThat(limiter.allow("A")).isTrue(); // Advance a tiny amount to model time moving between requests clock.advance(Duration.ofNanos(1L)); assertThat(limiter.allow("A")).isFalse(); assertThat(limiter.allow("B")).isTrue(); // independent key assertThat(limiter.allow("B")).isFalse(); clock.advance(Duration.ofNanos(100L)); // new window for both at boundary assertThat(limiter.allow("A")).isTrue(); assertThat(limiter.allow("B")).isTrue(); } @Disabled("Remove to run test") @Test @DisplayName("Long gaps reset window") void longGapsResetWindow() { TimeSource clock = new TimeSource(Instant.EPOCH.plusNanos(1_000L)); RateLimiter limiter = new RateLimiter<>(2, Duration.ofNanos(50L), clock); assertThat(limiter.allow("X")).isTrue(); clock.advance(Duration.ofNanos(1L)); assertThat(limiter.allow("X")).isTrue(); assertThat(limiter.allow("X")).isFalse(); // Advance several windows worth clock.advance(Duration.ofNanos(1_000L)); assertThat(limiter.allow("X")).isTrue(); assertThat(limiter.allow("X")).isTrue(); assertThat(limiter.allow("X")).isFalse(); } @Disabled("Remove to run test") @Test @DisplayName("Exact boundary starts a new window each time") void exactBoundaryIsNewWindowEveryTime() { TimeSource clock = new TimeSource(Instant.EPOCH); RateLimiter limiter = new RateLimiter<>(1, Duration.ofNanos(10L), clock); assertThat(limiter.allow("k")).isTrue(); assertThat(limiter.allow("k")).isFalse(); // Move exactly to boundary repeatedly; each time should allow once for (int i = 0; i < 5; i++) { clock.advance(Duration.ofNanos(10L)); assertThat(limiter.allow("k")).isTrue(); assertThat(limiter.allow("k")).isFalse(); } } @Disabled("Remove to run test") @Test @DisplayName("Supports UUID keys") void supportsUuidKeys() { TimeSource clock = new TimeSource(Instant.EPOCH); RateLimiter limiter = new RateLimiter<>(1, Duration.ofSeconds(1L), clock); UUID a = UUID.fromString("00000000-0000-0000-0000-000000000001"); UUID b = UUID.fromString("00000000-0000-0000-0000-000000000002"); assertThat(limiter.allow(a)).isTrue(); assertThat(limiter.allow(a)).isFalse(); // Advance slightly so the second client's window anchors later clock.advance(Duration.ofMillis(1L)); assertThat(limiter.allow(b)).isTrue(); assertThat(limiter.allow(b)).isFalse(); // Advance exactly one second to hit the window boundary clock.advance(Duration.ofSeconds(1L)); assertThat(limiter.allow(a)).isTrue(); assertThat(limiter.allow(b)).isTrue(); } @Disabled("Remove to run test") @Test @DisplayName("Supports Integer keys") void supportsIntegerKeys() { TimeSource clock = new TimeSource(Instant.EPOCH); RateLimiter limiter = new RateLimiter<>(1, Duration.ofNanos(100L), clock); assertThat(limiter.allow(42)).isTrue(); assertThat(limiter.allow(42)).isFalse(); clock.advance(Duration.ofNanos(1L)); assertThat(limiter.allow(84)).isTrue(); // independent key of different type assertThat(limiter.allow(84)).isFalse(); clock.advance(Duration.ofNanos(100L)); // boundary resets both assertThat(limiter.allow(42)).isTrue(); assertThat(limiter.allow(84)).isTrue(); } @Disabled("Remove to run test") @Test @DisplayName("Supports Long keys") void supportsLongKeys() { TimeSource clock = new TimeSource(Instant.EPOCH); RateLimiter limiter = new RateLimiter<>(2, Duration.ofNanos(50L), clock); assertThat(limiter.allow(1L)).isTrue(); assertThat(limiter.allow(1L)).isTrue(); assertThat(limiter.allow(1L)).isFalse(); clock.advance(Duration.ofNanos(1L)); assertThat(limiter.allow(2L)).isTrue(); // independent key assertThat(limiter.allow(2L)).isTrue(); assertThat(limiter.allow(2L)).isFalse(); clock.advance(Duration.ofNanos(50L)); assertThat(limiter.allow(1L)).isTrue(); assertThat(limiter.allow(2L)).isTrue(); } }