Pass a list of string values to a parameterized JUnit test

Question

I am trying to pass a collection of string values from a properties file to a parameterized JUnit test. Properties.values() returns Collection while JUnit requires the parameters be passed in Collection structure.

Does that mean I have to convert Collection<Object> to Collection<Object[]>, where each array is actually a single item?

I tried this:

Arrays.asList(new Object[][] {{theProperties.values()}});

But this puts all the values together in one Object and does not create a Collection as I expect it to. Can someone please help?

nhylated · Accepted Answer · 2015-01-12T17:21:49.813

4

Looks like parameterized JUnit tests requires a Collection even if each test has a single parameter.

Converting a Collection to Collection:

Using Java 8:

Collection<String> c = Arrays.asList("a", "b");
Collection<Object[]> co = c.stream()
                            .map(ele -> new Object[]{ele})
                            .collect(Collectors.toList());

Using Java 7 or below:

Collection<String> coll = Arrays.asList("a", "b");
Collection<Object[]> params = new ArrayList<Object[]>();
for (String s : coll) {
    params.add(new Object[] { s });
}

For Java 7 or below, you can either:

write a for loop (as shown above) or
use Apache Commons CollectionUtils#collect with a Transformer or
use Guava's Collections2#transform with a function

edited Jan 12 '15 at 17:21

answered Jan 09 '15 at 22:03

nhylated

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Can you please tell me how I can do it in a loop in Java 7? I am getting a little confused there. – techjourneyman Jan 12 '15 at 16:20
@naspras If my answer addresses your question, please mark it as the correct answer. – nhylated Jan 12 '15 at 17:49

Pass a list of string values to a parameterized JUnit test

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