BAEL-5625 bigdecimal =0 article (#12266)

java-numbers-4/src/test/java/com/baeldung/bigdecimalzero/BigDecimalZeroChkUnitTest.java

@@ -0,0 +1,34 @@
+package com.baeldung.bigdecimalzero;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.math.BigDecimal;
+
+import org.junit.jupiter.api.Test;
+
+class BigDecimalZeroChkUnitTest {
+    private static final BigDecimal BD1 = new BigDecimal("0");
+    private static final BigDecimal BD2 = new BigDecimal("0.0000");
+
+    @Test
+    void givenBD_whenCheckedWithEquals_shouldCheckedAsZero() {
+        assertThat(BigDecimal.ZERO.equals(BD1)).isTrue();
+
+        // in the article, we show the failure of the assertion below
+        // assertThat(BigDecimal.ZERO.equals(BD2)).isTrue();
+
+        assertThat(BigDecimal.ZERO.equals(BD2)).isFalse();
+    }
+
+    @Test
+    void givenBD_whenCheckedWithCompareTo_shouldCheckedAsZero() {
+        assertThat(BigDecimal.ZERO.compareTo(BD1)).isSameAs(0);
+        assertThat(BigDecimal.ZERO.compareTo(BD2)).isSameAs(0);
+    }
+
+    @Test
+    void givenBD_whenCheckedWithSignum_shouldCheckedAsZero() {
+        assertThat(BD1.signum()).isSameAs(0);
+        assertThat(BD2.signum()).isSameAs(0);
+    }
+}