diff --git a/.vscode/settings.json b/.vscode/settings.json
index ef16fa1aa7ac..72c0a22447b6 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -1,5 +1,10 @@
 {
     "githubPullRequests.ignoredPullRequestBranches": [
         "master"
-    ]
+    ],
+    "python.testing.pytestArgs": [
+        "."
+    ],
+    "python.testing.unittestEnabled": false,
+    "python.testing.pytestEnabled": true
 }
diff --git a/graphs/directed_and_undirected_weighted_graph.py b/graphs/directed_and_undirected_weighted_graph.py
index 8ca645fdace8..16271f6d63a6 100644
--- a/graphs/directed_and_undirected_weighted_graph.py
+++ b/graphs/directed_and_undirected_weighted_graph.py
@@ -8,12 +8,37 @@
 
 class DirectedGraph:
     def __init__(self):
+        """
+        Initialize an empty directed graph.
+
+        Example:
+        >>> g = DirectedGraph()
+        >>> g.graph
+        {}
+        """
         self.graph = {}
 
     # adding vertices and edges
     # adding the weight is optional
     # handles repetition
     def add_pair(self, u, v, w=1):
+        """
+        Add a directed edge with an optional weight.
+
+        Args:
+            u: Starting node.
+            v: Destination node.
+            w: Weight (default is 1).
+
+        Example:
+        >>> g = DirectedGraph()
+        >>> g.add_pair(1, 2)
+        >>> g.graph
+        {1: [[1, 2]], 2: []}
+        >>> g.add_pair(2, 3, 5)
+        >>> g.graph
+        {1: [[1, 2]], 2: [[5, 3]], 3: []}
+        """
         if self.graph.get(u):
             if self.graph[u].count([w, v]) == 0:
                 self.graph[u].append([w, v])
@@ -27,6 +52,21 @@ def all_nodes(self):
 
     # handles if the input does not exist
     def remove_pair(self, u, v):
+        """
+        Remove a directed edge from u to v.
+
+        Args:
+            u: Starting node.
+            v: Destination node.
+
+        Example:
+        >>> g = DirectedGraph()
+        >>> g.add_pair(1, 2)
+        >>> g.add_pair(1, 3)
+        >>> g.remove_pair(1, 2)
+        >>> g.graph
+        {1: [[1, 3]], 2: [], 3: []}
+        """
         if self.graph.get(u):
             for _ in self.graph[u]:
                 if _[1] == v:
@@ -487,3 +527,9 @@ def bfs_time(self, s=-2):
         self.bfs(s)
         end = time()
         return end - begin
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod(verbose=True)
diff --git a/greedy_methods/fractional_knapsack.py b/greedy_methods/fractional_knapsack.py
index d52b56f23569..f7455a9c9fce 100644
--- a/greedy_methods/fractional_knapsack.py
+++ b/greedy_methods/fractional_knapsack.py
@@ -39,9 +39,11 @@ def frac_knapsack(vl, wt, w, n):
     return (
         0
         if k == 0
-        else sum(vl[:k]) + (w - acc[k - 1]) * (vl[k]) / (wt[k])
-        if k != n
-        else sum(vl[:k])
+        else (
+            sum(vl[:k]) + (w - acc[k - 1]) * (vl[k]) / (wt[k])
+            if k != n
+            else sum(vl[:k])
+        )
     )
 
 
diff --git a/matrix/matrix_class.py b/matrix/matrix_class.py
index a5940a38e836..230eb95006fa 100644
--- a/matrix/matrix_class.py
+++ b/matrix/matrix_class.py
@@ -204,9 +204,11 @@ def cofactors(self) -> Matrix:
         return Matrix(
             [
                 [
-                    self.minors().rows[row][column]
-                    if (row + column) % 2 == 0
-                    else self.minors().rows[row][column] * -1
+                    (
+                        self.minors().rows[row][column]
+                        if (row + column) % 2 == 0
+                        else self.minors().rows[row][column] * -1
+                    )
                     for column in range(self.minors().num_columns)
                 ]
                 for row in range(self.minors().num_rows)