[Slim4] Add integration tests

Created by: ybelenko

PR checklist

• Read the contribution guidelines.
• If contributing template-only or documentation-only changes which will change sample output, build the project before.
• Run the shell script(s) under ./bin/ (or Windows batch scripts under.\bin\windows) to update Petstore samples related to your fix. This is important, as CI jobs will verify all generator outputs of your HEAD commit, and these must match the expectations made by your contribution. You only need to run ./bin/{LANG}-petstore.sh, ./bin/openapi3/{LANG}-petstore.sh if updating the code or mustache templates for a language ({LANG}) (e.g. php, ruby, python, etc).
• File the PR against the correct branch: master, 4.3.x, 5.0.x. Default: master.
• Copy the technical committee to review the pull request if your PR is targeting a particular programming language.

I didn't add run of PHP_CodeSniffer(popular PHP linter) on purpose. I think that there will be code styling issues which cannot be solved automatically because of mustaches. For instance I had problems with multiline mustache values. If value contains line breaks and indentations I cannot align it with other parts of the script. PHP_CodeSniffer will always complain about wrong indentations, so integration test will be failed. Anyway, syntax check + unit tests gives 100% workable build, while code formatting may be not perfect.

Current integration test process:

1. Composer dependencies install
2. Full PHP syntax check by phplint package
3. Tests run by PHPUnit.

modules/openapi-generator/src/main/resources/php-slim4-server/.gitignore

@@ -5,7 +5,7 @@ composer.phar
 
 # Commit your application's lock file https://getcomposer.org/doc/01-basic-usage.md#commit-your-composer-lock-file-to-version-control
 # You may choose to ignore a library lock file http://getcomposer.org/doc/02-libraries.md#lock-file
-# composer.lock
+composer.lock
 
 # phplint tool creates cache file which is not necessary in a codebase
 /.phplint-cache

samples/server/petstore/php-slim4/.gitignore

@@ -5,7 +5,7 @@ composer.phar
 
 # Commit your application's lock file https://getcomposer.org/doc/01-basic-usage.md#commit-your-composer-lock-file-to-version-control
 # You may choose to ignore a library lock file http://getcomposer.org/doc/02-libraries.md#lock-file
-# composer.lock
+composer.lock
 
 # phplint tool creates cache file which is not necessary in a codebase
 /.phplint-cache

samples/server/petstore/php-slim4/php_syntax_checker.bash

-#!/bin/bash
-# a simple script to perform a syntax check on php files using "php -l"
-
-for i in $( find . -name "*.php" ); do
-    result=`php -l $i | grep "No syntax errors detected"`
-    exit_status=$?
-    if [ $exit_status -eq 1 ]; then
-        echo "Syntax errors with $i"
-        exit 1;
-    fi
-done

samples/server/petstore/php-slim4/pom.xml

@@ -26,6 +26,19 @@
                 <artifactId>exec-maven-plugin</artifactId>
                 <version>1.2.1</version>
                 <executions>
+                    <execution>
+                        <id>bundle-install</id>
+                        <phase>pre-integration-test</phase>
+                        <goals>
+                            <goal>exec</goal>
+                        </goals>
+                        <configuration>
+                            <executable>composer</executable>
+                            <arguments>
+                                <argument>install</argument>
+                            </arguments>
+                        </configuration>
+                    </execution>
                     <execution>
                         <id>syntax-check</id>
                         <phase>integration-test</phase>
@@ -33,7 +46,23 @@
                             <goal>exec</goal>
                         </goals>
                         <configuration>
-                            <executable>./php_syntax_checker.bash</executable>
+                            <executable>composer</executable>
+                            <arguments>
+                                <argument>phplint</argument>
+                            </arguments>
+                        </configuration>
+                    </execution>
+                    <execution>
+                        <id>bundle-test</id>
+                        <phase>integration-test</phase>
+                        <goals>
+                            <goal>exec</goal>
+                        </goals>
+                        <configuration>
+                            <executable>composer</executable>
+                            <arguments>
+                                <argument>test</argument>
+                            </arguments>
                         </configuration>
                     </execution>
                 </executions>