[PHP] Run unit tests on 'tests' directory

[ackintosh]

PR checklist

• Read the contribution guidelines.
• Ran the shell script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh and ./bin/security/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates). Windows batch files can be found in .\bin\windows\.
• Filed the PR against the correct branch: 3.0.0 branch for changes related to OpenAPI spec 3.0. Default: master.
• Copied the technical committee to review the pull request if your PR is targeting a particular programming language.

Description of the PR

By #7200, the test directory is completely cleaned and all the test code is integrated into tests. So we have to run unit tests which in the tests directory.

[ackintosh]

https://travis-ci.org/swagger-api/swagger-codegen/builds/342288933#L5767

🤔 💦

[ERROR] Failed to execute goal org.codehaus.mojo:exec-maven-plugin:1.2.1:exec (bundle-test) on project PhpPetstoreClientTests: Command execution failed. Cannot run program "vendor/bin/phpunit tests" (in directory "/home/travis/build/swagger-api/swagger-codegen/samples/client/petstore/php/SwaggerClient-php"): error=2, No such file or directory -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException
[ERROR]
[ERROR] After correcting the problems, you can resume the build with the command
[ERROR] mvn -rf :PhpPetstoreClientTests

[wing328]

@ackintosh no worry. I'll take a look later this week.

[wing328]

You need to do something like the following instead:

                        <configuration>
                            <executable>vendor/bin/phpunit</executable>
                            <arguments>
                                <argument>tests</argument>
                            </arguments>
                        </configuration>

[ackintosh]

Thanks 😭 ✨

[ackintosh]

https://travis-ci.org/swagger-api/swagger-codegen/builds/343299617?utm_source=github_status&utm_medium=notification

1. Swagger\Client\PetApiTest::testInvalidArgument
   Failed asserting that exception of type "\InvalidArgumentException" is thrown.

swagger-codegen/samples/client/petstore/php/SwaggerClient-php/tests/PetApiTest.php

Lines 381 to 385 in 47614bb

	public function testInvalidArgument()
	{
	// the argument is required, and we must specify one or some from 'available', 'pending', 'sold'
	$this->api->findPetsByStatus([]);
	}

hmm...
I think this means that we have a different issue: PetApi::findPetsByStatus() accepts an empty array 😕
PetApi::findPetsByStatus() should throw an exception if an empty array is passed.