Update tox syntax and pin min tox version

setup.py

@@ -56,7 +56,7 @@ REQS_OPENSTACK = [
 REQS_FULL = REQS_AWS + REQS_GCP + REQS_OPENSTACK + REQS_AZURE
 # httpretty is required with/for moto 1.0.0 or AWS tests fail
 REQS_DEV = ([
-    'tox>=2.1.1',
+    'tox>=4.0.0',
     'pytest',
     'moto>=3.1.18',
     'sphinx>=1.3.1',

tox.ini

@@ -23,11 +23,48 @@ setenv =
     COVERAGE_FILE=.coverage.{envname}
 passenv =
     PYTHONUNBUFFERED
-    aws: CB_IMAGE_AWS,CB_VM_TYPE_AWS,CB_PLACEMENT_AWS,AWS_ACCESS_KEY,AWS_SECRET_KEY
-    azure: CB_IMAGE_AZURE,CB_VM_TYPE_AZURE,AZURE_SUBSCRIPTION_ID,AZURE_CLIENT_ID,AZURE_SECRET,AZURE_TENANT,AZURE_REGION_NAME,AZURE_RESOURCE_GROUP,AZURE_STORAGE_ACCOUNT,AZURE_VM_DEFAULT_USER_NAME,AZURE_PUBLIC_KEY_STORAGE_TABLE_NAME
-    gcp: CB_IMAGE_GCP,CB_VM_TYPE_GCP,CB_PLACEMENT_GCP,GCP_DEFAULT_REGION,GCP_DEFAULT_ZONE,GCP_PROJECT_NAME,GCP_SERVICE_CREDS_FILE,GCP_SERVICE_CREDS_DICT
-    openstack: CB_IMAGE_OS,CB_VM_TYPE_OS,CB_PLACEMENT_OS,OS_AUTH_URL,OS_PASSWORD,OS_PROJECT_NAME,OS_TENANT_NAME,OS_USERNAME,OS_REGION_NAME,OS_USER_DOMAIN_NAME,OS_PROJECT_DOMAIN_NAME,NOVA_SERVICE_NAME,OS_APPLICATION_CREDENTIAL_ID,OS_APPLICATION_CREDENTIAL_SECRET
-    mock: CB_IMAGE_AWS,CB_VM_TYPE_AWS,CB_PLACEMENT_AWS,AWS_ACCESS_KEY,AWS_SECRET_KEY
+    aws: CB_IMAGE_AWS
+    aws: CB_VM_TYPE_AWS
+    aws: CB_PLACEMENT_AWS
+    aws: AWS_ACCESS_KEY
+    aws: AWS_SECRET_KEY
+    azure: CB_IMAGE_AZURE
+    azure: CB_VM_TYPE_AZURE
+    azure: AZURE_SUBSCRIPTION_ID
+    azure: AZURE_CLIENT_ID,AZURE_SECRET
+    azure: AZURE_TENANT
+    azure: AZURE_REGION_NAME
+    azure: AZURE_RESOURCE_GROUP
+    azure: AZURE_STORAGE_ACCOUNT
+    azure: AZURE_VM_DEFAULT_USER_NAME
+    azure: AZURE_PUBLIC_KEY_STORAGE_TABLE_NAME
+    gcp: CB_IMAGE_GCP
+    gcp: CB_VM_TYPE_GCP
+    gcp: CB_PLACEMENT_GCP
+    gcp: GCP_DEFAULT_REGION
+    gcp: GCP_DEFAULT_ZONE
+    gcp: GCP_PROJECT_NAME
+    gcp: GCP_SERVICE_CREDS_FILE
+    gcp: GCP_SERVICE_CREDS_DICT
+    openstack: CB_IMAGE_OS
+    openstack: CB_VM_TYPE_OS
+    openstack: CB_PLACEMENT_OS
+    openstack: OS_AUTH_URL
+    openstack: OS_PASSWORD
+    openstack: OS_PROJECT_NAME
+    openstack: OS_TENANT_NAME
+    openstack: OS_USERNAME
+    openstack: OS_REGION_NAME
+    openstack: OS_USER_DOMAIN_NAME
+    openstack: OS_PROJECT_DOMAIN_NAME
+    openstack: NOVA_SERVICE_NAME
+    openstack: OS_APPLICATION_CREDENTIAL_ID
+    openstack: OS_APPLICATION_CREDENTIAL_SECRET
+    mock: CB_IMAGE_AWS
+    mock: CB_VM_TYPE_AWS
+    mock: CB_PLACEMENT_AWS
+    mock: AWS_ACCESS_KEY
+    mock: AWS_SECRET_KEY
 deps =
     -rrequirements.txt
     coverage