adding coverage duty

duties.py

@@ -8,9 +8,24 @@ def test(ctx):
 
 @duty
 def update_deps(ctx, dry: bool = True):
-    # duty update_deps dry=False
+    """Update the dependencies using Poetry.
+
+    Example:
+        `duty update_deps dry=False`
+    """
     dry_run = "--dry-run" if dry else ""
     ctx.run(
         ["poetry", "update", dry_run],
         title=f"Updating poetry deps {dry_run}",
     )
+
+
+@duty
+def coverage(ctx):
+    """Generate a coverage HTML report.
+
+    Example:
+        `duty coverage`
+    """
+    ctx.run(["coverage", "run", "--source", "tembo", "-m", "pytest"])
+    ctx.run(["coverage", "html"])