Assertj-core: Files#temporaryFolder() will fail if System temporary folder does not exist

[GencoreOperative]

Summary

We noticed this issue when working on a docker based build. We found that the Java defined property for java.io.tmpdir was defined but the folder did _not exist_. This caused calls to Files#temporaryFolder to fail with the exception:

org.assertj.core.api.exception.RuntimeIOException: Unable to find temporary directory

Example

    public static void main(String ... args) {
        System.setProperty("java.io.tmpdir", "badger");
        assertThat(new File(System.getProperty("java.io.tmpdir"))).doesNotExist();
        Files.temporaryFolder(); // Will fail
    }

The following code sample would resolve this issue. I am happy to raise this as a pull request if this issue is considered valid.

    public static File temporaryFolder() {
        File temp = new File(Files.temporaryFolderPath());
        if (!temp.isDirectory()) {
            throw new RuntimeIOException("Unable to find temporary directory");
        }
        if (!temp.exists() && !temp.mkdirs()) {
            throw new RuntimeIOException("Failed to create temporary directory");
        }
        return temp;
    }

[Sunt-ing]

If no one is working on this issue, I'd like to work on it. @joel-costigliola

[joel-costigliola]

Sure, go for it @Sunt-ing

[Sunt-ing]

So when we only set the property for java.io.tmpdir like System.setProperty("java.io.tmpdir", "badger");, although there is no temporary folder, we don't want Files.temporaryFolder(); to fail, right?

[joel-costigliola]

What needs to be done here is trying to create the directory if it does not exist

[scordio]

This seems to be an old feature which probably doesn't make sense anymore, considering that for example JUnit 4 and 5 have already good support for temporary directories.

I'd propose not to spend effort on it and to deprecate this api.

[Sunt-ing]

It seems that we should close this issue now.

[joel-costigliola]

let's just deprecate it and then we can close it

[Sunt-ing]

Should I add an annotation @depracated before the method File temporaryFolder() and then create a PR?

[joel-costigliola]

Sure, also add in javadoc a deprected annotation and explain the alternatives (JUnit 5 + JUnit 4)

[Sunt-ing]

OK. Please check this simple PR first: #1851