feat: Add job fair status tracking and corresponding unit tests

ruoyi-bussiness/src/test/java/com/ruoyi/cms/service/rc/impl/PublicJobFairServiceImplTest.java

@@ -0,0 +1,46 @@
+package com.ruoyi.cms.service.rc.impl;
+
+import org.junit.jupiter.api.Test;
+
+import java.util.Date;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+class PublicJobFairServiceImplTest
+{
+    private static final Date START_TIME = new Date(1_000L);
+    private static final Date END_TIME = new Date(2_000L);
+
+    @Test
+    void statusIsNotStartedBeforeStartTime()
+    {
+        assertEquals("未举办", resolveStatus(new Date(999L)));
+    }
+
+    @Test
+    void statusIsInProgressWithinTimeRangeIncludingBoundaries()
+    {
+        assertEquals("正在举办", resolveStatus(START_TIME));
+        assertEquals("正在举办", resolveStatus(new Date(1_500L)));
+        assertEquals("正在举办", resolveStatus(END_TIME));
+    }
+
+    @Test
+    void statusIsFinishedAfterEndTime()
+    {
+        assertEquals("已举办", resolveStatus(new Date(2_001L)));
+    }
+
+    @Test
+    void statusIsUnknownWhenTimeRangeIsIncomplete()
+    {
+        assertNull(PublicJobFairServiceImpl.resolveJobFairStatus(null, END_TIME, START_TIME));
+        assertNull(PublicJobFairServiceImpl.resolveJobFairStatus(START_TIME, null, END_TIME));
+    }
+
+    private String resolveStatus(Date now)
+    {
+        return PublicJobFairServiceImpl.resolveJobFairStatus(START_TIME, END_TIME, now);
+    }
+}