diff --git a/core-java-modules/core-java-string-conversions-3/src/test/java/com/baeldung/stringtolong/StringToLongPrimitiveOrLongObjectUnitTest.java b/core-java-modules/core-java-string-conversions-3/src/test/java/com/baeldung/stringtolong/StringToLongPrimitiveOrLongObjectUnitTest.java
new file mode 100644
index 0000000000..50201c8e89
--- /dev/null
+++ b/core-java-modules/core-java-string-conversions-3/src/test/java/com/baeldung/stringtolong/StringToLongPrimitiveOrLongObjectUnitTest.java
@@ -0,0 +1,89 @@
+package com.baeldung.stringtolong;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.apache.commons.lang3.math.NumberUtils;
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import com.google.common.primitives.Longs;
+
+public class StringToLongPrimitiveOrLongObjectUnitTest {
+
+    @Test
+    public void givenString_whenUsingLongConstructor_thenObtainLongObject() {
+        Long l = new Long("123456");
+        assertThat(l).isEqualTo(123456L);
+    }
+
+    @Test
+    public void givenInvalidString_whenUsingLongConstructor_thenNumberFormatExceptionThrown() {
+        Assertions.assertThrows(NumberFormatException.class, () -> new Long("Invalid String"));
+    }
+
+    @Test
+    public void givenString_whenUsingLongValueOf_thenObtainLongObject() {
+        Long l = Long.valueOf("123456");
+        assertThat(l).isEqualTo(123456L);
+    }
+
+    @Test
+    public void givenInvalidString_whenUsingLongValueOf_thenNumberFormatExceptionThrown() {
+        Assertions.assertThrows(NumberFormatException.class, () -> Long.valueOf("Invalid String"));
+    }
+
+    @Test
+    public void givenString_whenUsingParseLong_thenObtainLongPrimitive() {
+        long l = Long.parseLong("123456");
+        assertThat(l).isEqualTo(123456L);
+    }
+
+    @Test
+    public void givenInvalidString_whenUsingParseLong_thenNumberFormatExceptionThrown() {
+        Assertions.assertThrows(NumberFormatException.class, () -> Long.parseLong("Invalid String"));
+    }
+
+    @Test
+    public void givenHexadecimalString_whenUsingLongDecode_thenObtainLongObject() {
+        Long l = Long.decode("0x1e240");
+        assertThat(l).isEqualTo(123456L);
+    }
+
+    @Test
+    public void givenInvalidString_whenUsingLongDecode_thenNumberFormatExceptionThrown() {
+        Assertions.assertThrows(NumberFormatException.class, () -> Long.decode("Invalid String"));
+    }
+
+    @Test
+    public void givenHexadecimalString_whenUsingApacheCommons_thenObtainLongObject() {
+        Long l = NumberUtils.createLong("0x1e240");
+        assertThat(l).isEqualTo(123456L);
+    }
+
+    @Test
+    public void givenInvalidString_whenUsingApacheCommons_thenNumberFormatExceptionThrown() {
+        Assertions.assertThrows(NumberFormatException.class, () -> NumberUtils.createLong("Invalid String"));
+    }
+
+    @Test
+    public void givenString_whenUsingGuava_thenObtainLongObject() {
+        Long l = Longs.tryParse("123456");
+        assertThat(l).isEqualTo(123456L);
+    }
+
+    @Test
+    public void givenInvalidString_whenUsingGuava_thenObtainNull() {
+        assertThat(Longs.tryParse("Invalid String")).isNull();
+    }
+
+    @Test
+    public void givenString_whenUsingParseUnsignedLong_thenObtainUnsignedLongObject() {
+        Long l = Long.parseUnsignedLong("9223372036854775808");
+        assertThat(Long.toUnsignedString(l)).isEqualTo("9223372036854775808");
+    }
+
+    @Test
+    public void givenInvalidString_whenUsingParseUnsignedLong_thenNumberFormatExceptionThrown() {
+        Assertions.assertThrows(NumberFormatException.class, () -> Long.parseUnsignedLong("Invalid String"));
+    }
+}
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