Use upper case for environment variable.

.travis.yml

@@ -21,17 +21,17 @@ matrix:
 
   include:
     - php: 7.2
-      env: CODECOVERAGE=1 DB=mysql db_dsn='mysql://root@127.0.0.1/cakephp_test?init[]=SET sql_mode = "STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION"'
+      env: CODECOVERAGE=1 DB=mysql DB_DSN='mysql://root@127.0.0.1/cakephp_test?init[]=SET sql_mode = "STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION"'
     - php: 7.2
-      env: CODECOVERAGE=1 DB=pgsql db_dsn='postgres://postgres@127.0.0.1/cakephp_test'
+      env: CODECOVERAGE=1 DB=pgsql DB_DSN='postgres://postgres@127.0.0.1/cakephp_test'
     - php: 7.2
-      env: CODECOVERAGE=1 DB=sqlite db_dsn='sqlite:///:memory:'
+      env: CODECOVERAGE=1 DB=sqlite DB_DSN='sqlite:///:memory:'
     - php: 7.3
-      env: DB=mysql db_dsn='mysql://root@127.0.0.1/cakephp_test?init[]=SET sql_mode = "STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION"'
+      env: DB=mysql DB_DSN='mysql://root@127.0.0.1/cakephp_test?init[]=SET sql_mode = "STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION"'
     - php: 7.3
-      env: DB=pgsql db_dsn='postgres://postgres@127.0.0.1/cakephp_test'
+      env: DB=pgsql DB_DSN='postgres://postgres@127.0.0.1/cakephp_test'
     - php: 7.3
-      env: DB=sqlite db_dsn='sqlite:///:memory:'
+      env: DB=sqlite DB_DSN='sqlite:///:memory:'
     - php: '7.4snapshot'
 
   allow_failures:

phpunit.xml.dist

@@ -43,16 +43,16 @@
         <ini name="error_reporting" value="32767"/>
 
         <!-- SQLite
-        <env name="db_dsn" value="sqlite:///:memory:"/>
+        <env name="DB_DSN" value="sqlite:///:memory:"/>
         -->
         <!-- Postgres
-        <env name="db_dsn" value="postgres://localhost/cake_test?timezone=UTC"/>
+        <env name="DB_DSN" value="postgres://localhost/cake_test?timezone=UTC"/>
         -->
         <!-- Mysql
-        <env name="db_dsn" value="mysql://localhost/cake_test?timezone=UTC"/>
+        <env name="DB_DSN" value="mysql://localhost/cake_test?timezone=UTC"/>
         -->
         <!-- SQL Server
-        <env name="db_dsn" value="sqlserver://localhost/cake_test?timezone=UTC"/>
+        <env name="DB_DSN" value="sqlserver://localhost/cake_test?timezone=UTC"/>
         -->
     </php>
 </phpunit>

tests/bootstrap.php

@@ -96,12 +96,12 @@ Cache::setConfig([
 ]);
 
 // Ensure default test connection is defined
-if (!getenv('db_dsn')) {
-    putenv('db_dsn=sqlite:///:memory:');
+if (!getenv('DB_DSN')) {
+    putenv('DB_DSN=sqlite:///:memory:');
 }
 
-ConnectionManager::setConfig('test', ['url' => getenv('db_dsn')]);
-ConnectionManager::setConfig('test_custom_i18n_datasource', ['url' => getenv('db_dsn')]);
+ConnectionManager::setConfig('test', ['url' => getenv('DB_DSN')]);
+ConnectionManager::setConfig('test_custom_i18n_datasource', ['url' => getenv('DB_DSN')]);
 
 Configure::write('Session', [
     'defaults' => 'php',