diff --git a/annif/backend/__init__.py b/annif/backend/__init__.py
index 228ad051a..1b5b21651 100644
--- a/annif/backend/__init__.py
+++ b/annif/backend/__init__.py
@@ -1,7 +1,5 @@
 """Registry of backend types for Annif"""
 
-import configparser
-from flask import current_app
 from . import dummy
 from . import ensemble
 from . import http
diff --git a/annif/corpus/__init__.py b/annif/corpus/__init__.py
index 9f749f6cf..7d87d565a 100644
--- a/annif/corpus/__init__.py
+++ b/annif/corpus/__init__.py
@@ -7,3 +7,7 @@
 from .skos import SubjectFileSKOS
 from .types import Document
 from .combine import CombinedCorpus
+
+__all__ = [DocumentDirectory, DocumentFile, DocumentList, Subject,
+           SubjectDirectory, SubjectFileTSV, SubjectIndex, SubjectSet,
+           SubjectFileSKOS, Document, CombinedCorpus]
diff --git a/setup.py b/setup.py
index c60c90400..203fffe33 100644
--- a/setup.py
+++ b/setup.py
@@ -21,16 +21,19 @@ def read(fname):
     install_requires=[
         'connexion[swagger-ui]',
         'swagger_ui_bundle',
+        'flask',
         'flask-cors',
+        'click',
         'click-log',
         'nltk',
         'gensim',
         'sklearn',
         'rdflib'],
+    tests_require=['py', 'pytest', 'requests'],
     extras_require={
-        'fasttext': ['fasttextmirror'],
+        'fasttext': ['fasttext', 'fasttextmirror'],
         'voikko': ['voikko'],
-        'vw': ['vowpalwabbit'],
+        'vw': ['vowpalwabbit', 'numpy'],
     },
     entry_points={
         'console_scripts': ['annif=annif.cli:cli']},
diff --git a/tests/test_backend.py b/tests/test_backend.py
index 0b1073a9b..7a35bfee3 100644
--- a/tests/test_backend.py
+++ b/tests/test_backend.py
@@ -1,6 +1,5 @@
 """Unit tests for backends in Annif"""
 
-import os
 import pytest
 import annif
 import annif.backend
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 4d55a0edb..8fe8e883b 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -4,8 +4,6 @@
 import random
 import re
 import os.path
-import shutil
-import pytest
 from click.testing import CliRunner
 import annif.cli
 
diff --git a/tests/test_project.py b/tests/test_project.py
index 879118228..477cd0932 100644
--- a/tests/test_project.py
+++ b/tests/test_project.py
@@ -1,6 +1,5 @@
 """Unit tests for projects in Annif"""
 
-import os
 import pytest
 import annif.project
 import annif.backend.dummy
diff --git a/tests/test_rest.py b/tests/test_rest.py
index 4ecc57cc4..d6fafc183 100644
--- a/tests/test_rest.py
+++ b/tests/test_rest.py
@@ -1,6 +1,5 @@
 """Unit tests for REST API backend code in Annif"""
 
-import connexion
 import annif.rest