diff --git a/watson_developer_cloud/discovery_v1.py b/watson_developer_cloud/discovery_v1.py
index 0c7662ab..a4c88fc2 100644
--- a/watson_developer_cloud/discovery_v1.py
+++ b/watson_developer_cloud/discovery_v1.py
@@ -78,8 +78,8 @@ class DiscoveryV1(WatsonDeveloperCloudService):
         :return:
         """
         self._valid_name_and_description(name=name, description=description)
-        if size not in range(1, 4):
-            raise ValueError("Size can be 1, 2, or 3")
+        if size not in range(0, 4):
+            raise ValueError("Size can be 0, 1, 2, or 3")
 
         body = json.dumps({"name": name,
                            "description": description,

Discovery create_environment should allow size=0
https://github.com/watson-developer-cloud/python-sdk/blob/master/watson_developer_cloud/discovery_v1.py#L77

Actual API allows size=0 for free tier.
diff --git a/test/test_discovery_v1.py b/test/test_discovery_v1.py
index 90408da6..dcc06e60 100644
--- a/test/test_discovery_v1.py
+++ b/test/test_discovery_v1.py
@@ -2,6 +2,7 @@ import responses
 import os
 import json
 import watson_developer_cloud
+import pytest
 try:
     from urllib.parse import urlparse, urljoin
 except ImportError:
@@ -112,14 +113,12 @@ def test_create_environment():
 
     assert thrown
 
-    try:
+    with pytest.raises(ValueError):
         discovery.create_environment(size=14)
-    except ValueError as ve:
-        thrown = True
-        assert str(ve) == "Size can be 1, 2, or 3"
 
-    assert thrown
-    assert len(responses.calls) == 2
+    discovery.create_environment(size=0)
+
+    assert len(responses.calls) == 3
 
 
 @responses.activate

pip install -e .
parse_log_pytest
requirements.txt
pytest>=2.8.2 responses>=0.4.0 python_dotenv>=0.1.5 pytest
apt-get update apt-get install -y gcc
3.6
requirements.txt
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
attrs==22.2.0
certifi==2021.5.30
charset-normalizer==2.0.12
idna==3.10
importlib-metadata==4.8.3
iniconfig==1.1.1
packaging==21.3
pluggy==1.0.0
py==1.11.0
pyparsing==3.1.4
pysolr==3.10.0
pytest==7.0.1
python-dotenv==0.20.0
requests==2.27.1
responses==0.17.0
six==1.17.0
tomli==1.2.3
typing_extensions==4.1.1
urllib3==1.26.20
-e git+https://github.com/watson-developer-cloud/python-sdk.git@b35391e81bc3c3831239a6da8e9461bf6f8083ac#egg=watson_developer_cloud
zipp==3.6.0

name: python-sdk
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - ca-certificates=2025.2.25=h06a4308_0
  - certifi=2021.5.30=py36h06a4308_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.3=he6710b0_2
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - ncurses=6.4=h6a678d5_0
  - openssl=1.1.1w=h7f8727e_0
  - pip=21.2.2=py36h06a4308_0
  - python=3.6.13=h12debd9_1
  - readline=8.2=h5eee18b_0
  - setuptools=58.0.4=py36h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - wheel=0.37.1=pyhd3eb1b0_0
  - xz=5.6.4=h5eee18b_1
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - argparse==1.4.0
      - attrs==22.2.0
      - charset-normalizer==2.0.12
      - idna==3.10
      - importlib-metadata==4.8.3
      - iniconfig==1.1.1
      - packaging==21.3
      - pluggy==1.0.0
      - py==1.11.0
      - pyparsing==3.1.4
      - pysolr==3.10.0
      - pytest==7.0.1
      - python-dotenv==0.20.0
      - requests==2.27.1
      - responses==0.17.0
      - six==1.17.0
      - tomli==1.2.3
      - typing-extensions==4.1.1
      - urllib3==1.26.20
      - zipp==3.6.0
prefix: /opt/conda/envs/python-sdk

test/test_discovery_v1.py::test_create_environment
test/test_discovery_v1.py::test_environments test/test_discovery_v1.py::test_get_environment test/test_discovery_v1.py::test_update_environment test/test_discovery_v1.py::test_delete_environment test/test_discovery_v1.py::test_collections test/test_discovery_v1.py::test_collection test/test_discovery_v1.py::test_query test/test_discovery_v1.py::test_configs test/test_discovery_v1.py::test_empty_configs test/test_discovery_v1.py::test_no_configs test/test_discovery_v1.py::test_document
watson_developer_cloud/discovery_v1.py
watson_developer_cloud/discovery_v1.py