add shell.nix

shell.nix

@@ -0,0 +1,27 @@
+{ pkgs ? import <nixpkgs> {} }:
+pkgs.mkShell {
+  buildInputs = [
+    (pkgs.python3.withPackages (ps: [
+        ps.requests
+        # tests
+        ps.setuptools
+        ps.pytest
+        ps.mock
+        ps.requests-mock
+        ps.pandas
+      ])
+    )
+  ];
+
+  shellHook = ''
+    echo
+    echo '# blockfrost-python development shell'
+    echo
+    echo '## to run unit tests, use'
+    echo 'pytest'
+    echo
+    echo '## to run integration tests, use'
+    echo 'export BLOCKFROST_PROJECT_ID_MAINNET=mainnet..'
+    echo 'pytest'
+  '';
+}