JUnit Assert with BigDecimal
Solution 1:
The official junit solution to assert that two BigDecimal are matematically equal is to use hamcrest.
With java-hamcrest 2.0.0.0 we can use this syntax:
// import static org.hamcrest.MatcherAssert.assertThat;
// import org.hamcrest.Matchers;
BigDecimal a = new BigDecimal("100")
BigDecimal b = new BigDecimal("100.00")
assertThat(a, Matchers.comparesEqualTo(b));
Hamcrest 1.3 Quick Reference
Solution 2:
assertSame
checks if both objects are the same instance. assertEquals
checks if the numbers are equal in value and scale, that means i.e. 1000 is not equal to 1000.00. If you want to compare only the numeric value, you should use compareTo()
method from BigDecimal
.
For example:
BigDecimal bd1 = new BigDecimal (1000.00);
BigDecimal bd2 = new BigDecimal (1000);
org.junit.Assert.assertTrue(bd1.compareTo(bd2) == 0);
Solution 3:
Comparing BigDecimal
with compareTo()
works (as in: it ignore the scale and compare the actual number) but when unit testing it's useful to know what's the actual number, specially when the test fail.
An option I've used in this case is stripTrailingZeros()
on both BigDecimal
:
assertEquals(new BigDecimal("150").stripTrailingZeros(),
otherBigDecimal.stripTrailingZeros());
What this function does is remove zeroes without changing the number, so "150"
is converted in "1.5E+2"
: this way it doesn't matter if you have 150
, 150.00
or other form in otherBigDecimal
because they get normalized into the same form.
The only difference is a null
in otherBigDecimal
would give a NullPointerException
instead of an assertion error.
Solution 4:
assertSame
tests that the two objects are the same objects, i.e. that they are ==
:
Asserts that two objects refer to the same object. If they are not the same, an
AssertionError
without a message is thrown.
In your case, since bd1
and bd2
are both new BigDecimal
, the objects aren't the same, hence the exception.
What you want is to use assertEquals
, that tests if two objects are equal, i.e. .equals
:
Asserts that two objects are equal. If they are not, an
AssertionError
without a message is thrown. If expected and actual arenull
, they are considered equal.
BigDecimal bd1 = new BigDecimal (1000);
BigDecimal bd2 = new BigDecimal (1000);
org.junit.Assert.assertEquals(bd1,bd2);
Solution 5:
The method assertSame
tests that both are the same object. However, you have two objects which have the same value. To test this, you can use assertEquals
.
However, you should be aware of some unexpected behavior when using assertEquals
(which depends on the equals
method) on BigDecimal
s. For example, new BigDecimal("100").divide(new BigDecimal("10.0")).equals(new BigDecimal("10"))
evaluates to false
because equals
also looks at the scale of the BigDecimal
instances.
In many circumstances it is better to compare BigDecimal
s by using the compareTo
method:
assertTrue(bd1.compareTo(bd2) == 0);