test(lesson-17/bank): add AuditLog & TransactionEntry coverage

Author: tobyev

lesson_17/bank/bank_app/src/test/java/com/codedifferently/lesson17/bank/AuditLogTest.java

@@ -0,0 +1,54 @@
+package com.codedifferently.lesson17.bank;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import java.time.Instant;
+import java.util.List;
+import org.junit.jupiter.api.Test;
+
+class AuditLogTest {
+
+  @Test
+  void record_addsEntriesAndFieldsAreCorrect() {
+    AuditLog log = new AuditLog();
+    log.record("A-001", 100.0, TransactionType.DEPOSIT_CASH, "cash");
+    log.record("A-002", 25.5, TransactionType.WITHDRAWAL, "atm");
+    log.record("A-003", 75.0, TransactionType.DEPOSIT_CHECK, "Check");
+
+    List<TransactionEntry> entries = log.getEntries();
+    assertEquals(3, entries.size());
+
+    TransactionEntry e1 = entries.get(0);
+    assertEquals("A-001", e1.getAccountNumber());
+    assertEquals(100.0, e1.getAmount(), 0.0001);
+    assertEquals(TransactionType.DEPOSIT_CASH, e1.getType());
+    assertEquals("cash", e1.getNote());
+    assertNotNull(e1.getTimestamp());
+  }
+
+  @Test
+  void getEntries_isUnmodifiable() {
+    AuditLog log = new AuditLog();
+    log.record("A-100", 1.0, TransactionType.DEPOSIT_CASH, "x");
+    List<TransactionEntry> view = log.getEntries();
+    assertThrows(UnsupportedOperationException.class, () -> view.add(view.get(0)));
+  }
+
+  @Test
+  void transactionEntry_gettersReturnConstructorValues() {
+    Instant ts = Instant.parse("2020-01-01T00:00:00Z");
+    TransactionEntry entry =
+        new TransactionEntry(ts, "A-XYZ", 9.99, TransactionType.WITHDRAWAL, "atm");
+    assertEquals(ts, entry.getTimestamp());
+    assertEquals("A-XYZ", entry.getAccountNumber());
+    assertEquals(9.99, entry.getAmount(), 0.0001);
+    assertEquals(TransactionType.WITHDRAWAL, entry.getType());
+    assertEquals("atm", entry.getNote());
+  }
+
+  @Test
+  void bankAtm_exposesAuditLog() {
+    BankAtm atm = new BankAtm();
+    assertNotNull(atm.getAuditLog());
+  }
+}