diff --git a/README.md b/README.md
index 7be5db0..e0b7087 100644
--- a/README.md
+++ b/README.md
@@ -8,4 +8,12 @@ py-libp2p requires Python 3.6 and the best way to guarantee a clean Python 3.6 e
 virtualenv -p python3.6 venv
 . venv/bin/activate
 pip install -r requirements.txt
+```
+
+## Testing
+
+After installing our requirements (see above), you can:
+```sh
+cd tests
+pytest
 ```
\ No newline at end of file
diff --git a/peer/peerdata.py b/peer/peerdata.py
index 9a700d9..eec06cd 100644
--- a/peer/peerdata.py
+++ b/peer/peerdata.py
@@ -13,6 +13,9 @@ class PeerData(IPeerData):
     def add_protocols(self, protocols):
         self.protocols.extend(protocols)
 
+    def set_protocols(self, protocols):
+        self.protocols = protocols
+
     def add_addrs(self, addrs):
         self.addrs.extend(addrs)
 
diff --git a/peer/peerdata_interface.py b/peer/peerdata_interface.py
index dd4432d..b8e4e12 100644
--- a/peer/peerdata_interface.py
+++ b/peer/peerdata_interface.py
@@ -2,48 +2,62 @@ from abc import ABC, abstractmethod
 
 class IPeerData(ABC):
 
-    """
-    :return: all protocols associated with given peer
-    """
+    @abstractmethod
     def get_protocols(self):
+        """
+        :return: all protocols associated with given peer
+        """
         pass
 
-    """
-    :param protocols: protocols to add
-    """
+    @abstractmethod
     def add_protocols(self, protocols):
+        """
+        :param protocols: protocols to add
+        """
         pass
 
-    """
-    :param addrs: multiaddresses to add
-    """
+    @abstractmethod
+    def set_protocols(self, protocols):
+        """
+        :param protocols: protocols to add
+        """
+        pass
+
+    @abstractmethod
     def add_addrs(self, addrs):
+        """
+        :param addrs: multiaddresses to add
+        """
         pass
 
-    """
-    :return: all multiaddresses
-    """
+    @abstractmethod
     def get_addrs(self):
+        """
+        :return: all multiaddresses
+        """
         pass
 
-    """
-    Clear all addresses
-    """
+    @abstractmethod
     def clear_addrs(self):
+        """
+        Clear all addresses
+        """
         pass
 
-    """
-    :param key: key in KV pair
-    :param val: val to associate with key
-    :raise Exception: unsuccesful put
-    """
+    @abstractmethod
     def put_metadata(self, key, val):
+        """
+        :param key: key in KV pair
+        :param val: val to associate with key
+        :raise Exception: unsuccesful put
+        """
         pass
 
-    """
-    :param key: key in KV pair
-    :return: val for key
-    :raise Exception: key not found
-    """
+    @abstractmethod
     def get_metadata(self, key):
+        """
+        :param key: key in KV pair
+        :return: val for key
+        :raise Exception: key not found
+        """
         pass
diff --git a/peer/peerstore.py b/peer/peerstore.py
index 8db6a33..0745667 100644
--- a/peer/peerstore.py
+++ b/peer/peerstore.py
@@ -38,6 +38,10 @@ class PeerStore(IPeerStore):
         peer = self.__create_or_get_peer(peer_id)
         peer.add_protocols(protocols)
 
+    def set_protocols(self, peer_id, protocols):
+        peer = self.__create_or_get_peer(peer_id)
+        peer.set_protocols(protocols)
+
     def peers(self):
         return self.peer_map.keys()
 
@@ -55,7 +59,7 @@ class PeerStore(IPeerStore):
         peer.put_metadata(key, val)
 
     def add_addr(self, peer_id, addr, ttl):
-        self.add_addrs(self, peer_id, [addr])
+        self.add_addrs(peer_id, [addr], ttl)
 
     def add_addrs(self, peer_id, addrs, ttl):
         # Ignore ttl for now
diff --git a/peer/peerstore_interface.py b/peer/peerstore_interface.py
index 1f8d21c..0773621 100644
--- a/peer/peerstore_interface.py
+++ b/peer/peerstore_interface.py
@@ -2,7 +2,7 @@ from abc import ABC, abstractmethod
 from .addrbook_interface import IAddrBook
 from .peermetadata_interface import IPeerMetadata
 
-class IPeerStore(ABC, IAddrBook, IPeerMetadata):
+class IPeerStore(IAddrBook, IPeerMetadata):
 
     def __init__(self):
         IPeerMetadata.__init__(self)
diff --git a/tests/__init.py__ b/tests/__init__.py
similarity index 100%
rename from tests/__init.py__
rename to tests/__init__.py
diff --git a/tests/peer/__init__.py b/tests/peer/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/peer/test_addrbook.py b/tests/peer/test_addrbook.py
new file mode 100644
index 0000000..c67b74f
--- /dev/null
+++ b/tests/peer/test_addrbook.py
@@ -0,0 +1,59 @@
+import pytest
+
+from peer.peerstore import PeerStoreError
+from peer.peerstore import PeerStore
+
+# Testing methods from IAddrBook base class.
+
+
+def test_addrs_empty():
+    with pytest.raises(PeerStoreError):
+        store = PeerStore()
+        val = store.addrs("peer")
+        assert not val
+
+
+def test_add_addr_single():
+    store = PeerStore()
+    store.add_addr("peer1", "/foo", 10)
+    store.add_addr("peer1", "/bar", 10)
+    store.add_addr("peer2", "/baz", 10)
+
+    assert store.addrs("peer1") == ["/foo", "/bar"]
+    assert store.addrs("peer2") == ["/baz"]
+
+
+def test_add_addrs_multiple():
+    store = PeerStore()
+    store.add_addrs("peer1", ["/foo1", "/bar1"], 10)
+    store.add_addrs("peer2", ["/foo2"], 10)
+
+    assert store.addrs("peer1") == ["/foo1", "/bar1"]
+    assert store.addrs("peer2") == ["/foo2"]
+
+
+def test_clear_addrs():
+    store = PeerStore()
+    store.add_addrs("peer1", ["/foo1", "/bar1"], 10)
+    store.add_addrs("peer2", ["/foo2"], 10)
+    store.clear_addrs("peer1")
+
+    assert store.addrs("peer1") == []
+    assert store.addrs("peer2") == ["/foo2"]
+
+    store.add_addrs("peer1", ["/foo1", "/bar1"], 10)
+
+    assert store.addrs("peer1") == ["/foo1", "/bar1"]
+
+
+def test_peers_with_addrs():
+    store = PeerStore()
+    store.add_addrs("peer1", [], 10)
+    store.add_addrs("peer2", ["/foo"], 10)
+    store.add_addrs("peer3", ["/bar"], 10)
+
+    assert set(store.peers_with_addrs()) == set(["peer2", "peer3"])
+
+    store.clear_addrs("peer2")
+
+    assert set(store.peers_with_addrs()) == set(["peer3"])
diff --git a/tests/peer/test_peermetadata.py b/tests/peer/test_peermetadata.py
new file mode 100644
index 0000000..afc9c46
--- /dev/null
+++ b/tests/peer/test_peermetadata.py
@@ -0,0 +1,44 @@
+import pytest
+
+from peer.peerstore import PeerStoreError
+from peer.peerstore import PeerStore
+
+# Testing methods from IPeerMetadata base class.
+
+
+def test_get_empty():
+    with pytest.raises(PeerStoreError):
+        store = PeerStore()
+        val = store.get("peer", "key")
+        assert not val
+
+
+def test_put_get_simple():
+    store = PeerStore()
+    store.put("peer", "key", "val")
+    assert store.get("peer", "key") == "val"
+
+
+def test_put_get_update():
+    store = PeerStore()
+    store.put("peer", "key1", "val1")
+    store.put("peer", "key2", "val2")
+    store.put("peer", "key2", "new val2")
+
+    assert store.get("peer", "key1") == "val1"
+    assert store.get("peer", "key2") == "new val2"
+
+
+def test_put_get_two_peers():
+    store = PeerStore()
+    store.put("peer1", "key1", "val1")
+    store.put("peer2", "key1", "val1 prime")
+
+    assert store.get("peer1", "key1") == "val1"
+    assert store.get("peer2", "key1") == "val1 prime"
+
+    # Try update
+    store.put("peer2", "key1", "new val1")
+
+    assert store.get("peer1", "key1") == "val1"
+    assert store.get("peer2", "key1") == "new val1"
diff --git a/tests/peer/test_peerstore.py b/tests/peer/test_peerstore.py
new file mode 100644
index 0000000..d0200ea
--- /dev/null
+++ b/tests/peer/test_peerstore.py
@@ -0,0 +1,61 @@
+import pytest
+
+from peer.peerstore import PeerStoreError
+from peer.peerstore import PeerStore
+
+# Testing methods from IPeerStore base class.
+
+
+def test_peer_info_empty():
+    store = PeerStore()
+    info = store.peer_info("peer")
+
+    assert not info
+
+
+def test_peer_info_basic():
+    store = PeerStore()
+    store.add_addr("peer", "/foo", 10)
+    info = store.peer_info("peer")
+
+    assert info.peer_id == "peer"
+    assert info.addrs == ["/foo"]
+
+
+def test_add_get_protocols_basic():
+    store = PeerStore()
+    store.add_protocols("peer1", ["p1", "p2"])
+    store.add_protocols("peer2", ["p3"])
+
+    assert set(store.get_protocols("peer1")) == set(["p1", "p2"])
+    assert set(store.get_protocols("peer2")) == set(["p3"])
+
+
+def test_add_get_protocols_extend():
+    store = PeerStore()
+    store.add_protocols("peer1", ["p1", "p2"])
+    store.add_protocols("peer1", ["p3"])
+
+    assert set(store.get_protocols("peer1")) == set(["p1", "p2", "p3"])
+
+
+def test_set_protocols():
+    store = PeerStore()
+    store.add_protocols("peer1", ["p1", "p2"])
+    store.add_protocols("peer2", ["p3"])
+
+    store.set_protocols("peer1", ["p4"])
+    store.set_protocols("peer2", [])
+
+    assert set(store.get_protocols("peer1")) == set(["p4"])
+    assert set(store.get_protocols("peer2")) == set([])
+
+
+# Test with methods from other Peer interfaces.
+def test_peers():
+    store = PeerStore()
+    store.add_protocols("peer1", [])
+    store.put("peer2", "key", "val")
+    store.add_addr("peer3", "/foo", 10)
+
+    assert set(store.peers()) == set(["peer1", "peer2", "peer3"])
diff --git a/tests/test_example.py b/tests/test_example.py
index d61d9b6..41d6cb6 100644
--- a/tests/test_example.py
+++ b/tests/test_example.py
@@ -3,7 +3,7 @@ import pytest
 @pytest.mark.parametrize("test_input,expected", [
     ("3+5", 8),
     ("2+4", 6),
-    ("6*9", 42),
+    ("6*9", 54),
 ])
 def test_eval(test_input, expected):
     assert eval(test_input) == expected