diff --git a/tests/test_config.py b/tests/test_config.py
index 42ae459..d56659c 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -1,17 +1,263 @@
 """Test for the config.py."""
 
 # import pytest
+import os
 
 from cvejob.config import DefaultConfig, RuntimeConfig
 
 
-def test_default_config():
+def test_default_config_constructor():
     """Basic test for the class DefaultConfig."""
     config = DefaultConfig()
     assert config is not None
 
 
+def test_default_config_attributes():
+    """Check the attributes existence for a class DefaultConfig."""
+    config = DefaultConfig()
+
+    # basic configuration check
+    attributes = ("ecosystem", "cve_age", "feed_dir", "feed_names", "date_range", "cve_id",
+                  "package_name", "cpe2pkg_path", "pkgfile_dir", "use_nvdtoolkit",
+                  "nvdtoolkit_export_dir")
+    for attribute in attributes:
+        assert hasattr(config, attribute)
+
+
+def test_default_config_attribute_values_nil():
+    """Check the attributes that needs to be set to nil (None)."""
+    config = DefaultConfig()
+
+    # the following attributes needs to be set to nil
+    assert config.feed_names is None
+    assert config.date_range is None
+    assert config.cve_id is None
+    assert config.package_name is None
+    assert config.feed_names is None
+
+
+def test_default_config_attribute_values_not_nil():
+    """Check the attributes that needs not to be set to nil (None)."""
+    config = DefaultConfig()
+
+    # the following attributes need not be set to nil
+    assert config.ecosystem is not None
+    assert config.cve_age is not None
+    assert config.feed_dir is not None
+    assert config.cpe2pkg_path is not None
+    assert config.pkgfile_dir is not None
+    assert config.use_nvdtoolkit is not None
+    assert config.nvdtoolkit_export_dir is not None
+
+
 def test_runtime_config():
     """Basic test for the class RuntimeConfig."""
     config = RuntimeConfig()
     assert config is not None
+
+
+def test_runtime_config_attributes():
+    """Check the attributes existence for a class RuntimeConfig."""
+    config = RuntimeConfig()
+    assert config is not None
+
+    assert hasattr(config, "_config")
+
+
+def unset_environment_variable(name):
+    """Reset specified environment variable."""
+    return os.environ.pop(name, None)
+
+
+def test_runtime_config_attribute_ecosystem():
+    """Check the attributes handling for a class RuntimeConfig."""
+    old_value = unset_environment_variable('CVEJOB_ECOSYSTEM')
+
+    config = RuntimeConfig()
+    assert config._config.ecosystem == 'python'
+
+    os.environ['CVEJOB_ECOSYSTEM'] = 'foobar'
+    config = RuntimeConfig()
+    assert config._config.ecosystem == 'foobar'
+
+    if old_value is not None:
+        os.environ['CVEJOB_ECOSYSTEM'] = old_value
+
+
+def test_runtime_config_attribute_cve_age():
+    """Check the attributes handling for a class RuntimeConfig."""
+    old_value = unset_environment_variable('CVEJOB_CVE_AGE')
+
+    config = RuntimeConfig()
+    assert config._config.cve_age == 0
+
+    os.environ['CVEJOB_CVE_AGE'] = '42'
+    config = RuntimeConfig()
+    assert config._config.cve_age == 42
+
+    os.environ['CVEJOB_CVE_AGE'] = '-42'
+    config = RuntimeConfig()
+    assert config._config.cve_age == -42
+
+    if old_value is not None:
+        os.environ['CVEJOB_CVE_AGE'] = old_value
+
+
+def test_runtime_config_attribute_cvejob_feed_dir():
+    """Check the attributes handling for a class RuntimeConfig."""
+    old_value = unset_environment_variable('CVEJOB_FEED_DIR')
+
+    config = RuntimeConfig()
+    assert config._config.feed_dir == 'nvd-data/'
+
+    os.environ['CVEJOB_FEED_DIR'] = 'directory1'
+    config = RuntimeConfig()
+    assert config._config.feed_dir == 'directory1'
+
+    if old_value is not None:
+        os.environ['CVEJOB_FEED_DIR'] = old_value
+
+
+def test_runtime_config_attribute_cvejob_feed_names():
+    """Check the attributes handling for a class RuntimeConfig."""
+    old_value = unset_environment_variable('CVEJOB_FEED_NAMES')
+
+    config = RuntimeConfig()
+    assert config._config.feed_names is None
+
+    # TODO: the following test needs to be enabled after the fix in master branch
+    # os.environ['CVEJOB_FEED_NAMES'] = 'name1'
+    # config = RuntimeConfig()
+    # assert config._config.feed_names == ['name1']
+
+    # os.environ['CVEJOB_FEED_NAMES'] = 'name1,name2'
+    # config = RuntimeConfig()
+    # assert config._config.feed_names == ['name1', 'name2']
+
+    if old_value is not None:
+        os.environ['CVEJOB_FEED_NAMES'] = old_value
+
+
+def test_runtime_config_attribute_cvejob_date_range():
+    """Check the attributes handling for a class RuntimeConfig."""
+    old_value = unset_environment_variable('CVEJOB_DATE_RANGE')
+
+    config = RuntimeConfig()
+    assert config._config.date_range is None
+
+    os.environ['CVEJOB_DATE_RANGE'] = '2017-01-01'
+    config = RuntimeConfig()
+    assert config._config.date_range == '2017-01-01'
+
+    if old_value is not None:
+        os.environ['CVEJOB_DATE_RANGE'] = old_value
+
+
+def test_runtime_config_attribute_cvejob_cve_id():
+    """Check the attributes handling for a class RuntimeConfig."""
+    old_value = unset_environment_variable('CVEJOB_CVE_ID')
+
+    config = RuntimeConfig()
+    assert config._config.cve_id is None
+
+    os.environ['CVEJOB_CVE_ID'] = 'CVE1234'
+    config = RuntimeConfig()
+    assert config._config.cve_id == 'CVE1234'
+
+    if old_value is not None:
+        os.environ['CVEJOB_CVE_ID'] = old_value
+
+
+def test_runtime_config_attribute_cvejob_package_name():
+    """Check the attributes handling for a class RuntimeConfig."""
+    old_value = unset_environment_variable('CVEJOB_PACKAGE_NAME')
+
+    config = RuntimeConfig()
+    assert config._config.package_name is None
+
+    os.environ['CVEJOB_PACKAGE_NAME'] = 'test_package'
+    config = RuntimeConfig()
+    assert config._config.package_name == 'test_package'
+
+    if old_value is not None:
+        os.environ['CVEJOB_PACKAGE_NAME'] = old_value
+
+
+def test_runtime_config_attribute_cvejob_cpe2pkg_path():
+    """Check the attributes handling for a class RuntimeConfig."""
+    old_value = unset_environment_variable('CVEJOB_CPE2PKG_PATH')
+
+    config = RuntimeConfig()
+    assert config._config.cpe2pkg_path == 'cpe2pkg.jar'
+
+    os.environ['CVEJOB_CPE2PKG_PATH'] = 'cpe2pkg10.jar'
+    config = RuntimeConfig()
+    assert config._config.cpe2pkg_path == 'cpe2pkg10.jar'
+
+    if old_value is not None:
+        os.environ['CVEJOB_CPE2PKG_PATH'] = old_value
+
+
+def test_runtime_config_attribute_cvejob_pkgfile_dir():
+    """Check the attributes handling for a class RuntimeConfig."""
+    old_value = unset_environment_variable('CVEJOB_PKGFILE_DIR')
+
+    config = RuntimeConfig()
+    assert config._config.pkgfile_dir == 'data/'
+
+    os.environ['CVEJOB_PKGFILE_DIR'] = 'cpe2pkg10.jar'
+    config = RuntimeConfig()
+    assert config._config.pkgfile_dir == 'cpe2pkg10.jar'
+
+    if old_value is not None:
+        os.environ['CVEJOB_PKGFILE_DIR'] = old_value
+
+
+def test_runtime_config_attribute_cvejob_use_nvd_toolkit():
+    """Check the attributes handling for a class RuntimeConfig."""
+    old_value = unset_environment_variable('CVEJOB_USE_NVD_TOOLKIT')
+
+    config = RuntimeConfig()
+    assert not config._config.use_nvdtoolkit
+
+    os.environ['CVEJOB_USE_NVD_TOOLKIT'] = 'true'
+    config = RuntimeConfig()
+    assert config._config.use_nvdtoolkit
+
+    os.environ['CVEJOB_USE_NVD_TOOLKIT'] = '1'
+    config = RuntimeConfig()
+    assert config._config.use_nvdtoolkit
+
+    os.environ['CVEJOB_USE_NVD_TOOLKIT'] = 'yes'
+    config = RuntimeConfig()
+    assert config._config.use_nvdtoolkit
+
+    os.environ['CVEJOB_USE_NVD_TOOLKIT'] = 'false'
+    config = RuntimeConfig()
+    assert not config._config.use_nvdtoolkit
+
+    os.environ['CVEJOB_USE_NVD_TOOLKIT'] = '0'
+    config = RuntimeConfig()
+    assert not config._config.use_nvdtoolkit
+
+    os.environ['CVEJOB_USE_NVD_TOOLKIT'] = 'no'
+    config = RuntimeConfig()
+    assert not config._config.use_nvdtoolkit
+
+    if old_value is not None:
+        os.environ['CVEJOB_USE_NVD_TOOLKIT'] = old_value
+
+
+def test_runtime_config_attribute_cvejob_nvd_toolkit_export_dir():
+    """Check the attributes handling for a class RuntimeConfig."""
+    old_value = unset_environment_variable('CVEJOB_NVD_TOOLKIT_EXPORT_DIR')
+
+    config = RuntimeConfig()
+    assert config._config.nvdtoolkit_export_dir == 'export/'
+
+    os.environ['CVEJOB_NVD_TOOLKIT_EXPORT_DIR'] = 'export2/'
+    config = RuntimeConfig()
+    assert config._config.nvdtoolkit_export_dir == 'export2/'
+
+    if old_value is not None:
+        os.environ['CVEJOB_NVD_TOOLKIT_EXPORT_DIR'] = old_value