test: add unit tests for Alarm model class

ai-apm-web/src/test/java/com/databuff/apm/web/monitor/AlarmTest.java

@@ -0,0 +1,115 @@
+package com.databuff.apm.web.monitor;
+
+import org.junit.jupiter.api.Test;
+
+import java.time.Instant;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class AlarmTest {
+
+    @Test
+    void exposesExpectedStatusConstants() {
+        assertThat(Alarm.STATUS_OPEN).isEqualTo("open");
+        assertThat(Alarm.STATUS_RESOLVED).isEqualTo("resolved");
+    }
+
+    @Test
+    void constructsOpenAlarmWithAllComponents() {
+        Instant triggeredAt = Instant.parse("2026-07-10T08:00:00Z");
+        Alarm alarm = new Alarm(
+                "alarm-1",
+                42L,
+                "checkout",
+                "threshold",
+                "critical",
+                "error rate exceeded",
+                Alarm.STATUS_OPEN,
+                triggeredAt,
+                null);
+
+        assertThat(alarm.id()).isEqualTo("alarm-1");
+        assertThat(alarm.policyId()).isEqualTo(42L);
+        assertThat(alarm.service()).isEqualTo("checkout");
+        assertThat(alarm.detectionWay()).isEqualTo("threshold");
+        assertThat(alarm.level()).isEqualTo("critical");
+        assertThat(alarm.message()).isEqualTo("error rate exceeded");
+        assertThat(alarm.status()).isEqualTo(Alarm.STATUS_OPEN);
+        assertThat(alarm.triggeredAt()).isEqualTo(triggeredAt);
+        assertThat(alarm.resolvedAt()).isNull();
+    }
+
+    @Test
+    void constructsAlarmWithDifferentLevelAndStatus() {
+        Instant triggeredAt = Instant.parse("2026-07-10T08:00:00Z");
+        Instant resolvedAt = Instant.parse("2026-07-10T08:05:00Z");
+        Alarm alarm = new Alarm(
+                "alarm-2",
+                84L,
+                "payments",
+                "mutation",
+                "warning",
+                "request count changed",
+                Alarm.STATUS_RESOLVED,
+                triggeredAt,
+                resolvedAt);
+
+        assertThat(alarm.level()).isEqualTo("warning");
+        assertThat(alarm.status()).isEqualTo(Alarm.STATUS_RESOLVED);
+        assertThat(alarm.detectionWay()).isEqualTo("mutation");
+        assertThat(alarm.resolvedAt()).isEqualTo(resolvedAt);
+    }
+
+    @Test
+    void resolveReturnsResolvedCopyWithResolutionTime() {
+        Alarm alarm = sampleAlarm();
+        Instant resolvedAt = Instant.parse("2026-07-10T08:05:00Z");
+
+        Alarm resolved = alarm.resolve(resolvedAt);
+
+        assertThat(resolved.id()).isEqualTo(alarm.id());
+        assertThat(resolved.policyId()).isEqualTo(alarm.policyId());
+        assertThat(resolved.service()).isEqualTo(alarm.service());
+        assertThat(resolved.detectionWay()).isEqualTo(alarm.detectionWay());
+        assertThat(resolved.level()).isEqualTo(alarm.level());
+        assertThat(resolved.message()).isEqualTo(alarm.message());
+        assertThat(resolved.triggeredAt()).isEqualTo(alarm.triggeredAt());
+        assertThat(resolved.status()).isEqualTo(Alarm.STATUS_RESOLVED);
+        assertThat(resolved.resolvedAt()).isEqualTo(resolvedAt);
+    }
+
+    @Test
+    void resolveDoesNotMutateOriginalAlarm() {
+        Alarm alarm = sampleAlarm();
+
+        Alarm resolved = alarm.resolve(Instant.parse("2026-07-10T08:05:00Z"));
+
+        assertThat(alarm.status()).isEqualTo(Alarm.STATUS_OPEN);
+        assertThat(alarm.resolvedAt()).isNull();
+        assertThat(resolved).isNotSameAs(alarm);
+        assertThat(resolved).isNotEqualTo(alarm);
+    }
+
+    @Test
+    void recordEqualityHashCodeAndStringRepresentation() {
+        Alarm left = sampleAlarm();
+        Alarm right = sampleAlarm();
+
+        assertThat(left).isEqualTo(right);
+        assertThat(left.hashCode()).isEqualTo(right.hashCode());
+        assertThat(left.toString()).contains("alarm-1", "checkout", "threshold", "critical", "open");
+    }
+
+    private static Alarm sampleAlarm() {
+        return new Alarm(
+                "alarm-1",
+                42L,
+                "checkout",
+                "threshold",
+                "critical",
+                "error rate exceeded",
+                Alarm.STATUS_OPEN,
+                Instant.parse("2026-07-10T08:00:00Z"),
+                null);
+    }
+}