do not raise error if package is already installed #125

CHANGELOG.md

@@ -1,5 +1,6 @@
-0.12.4.0
+0.13.0.0
 * Add `runpip` command
+* Do not raise error when running `pipx install PACKAGE` and the package has already been installed by pipx (#125)
 
 0.12.3.3
 * Update logic in determining a package's binaries during installation. This removes spurious binaries from the installation. (#104)

pipx/commands.py

@@ -298,10 +298,12 @@ def install(
         if force:
             print(f"Installing to existing directory {str(venv_dir)!r}")
         else:
-            raise PipxError(
-                f"Not installing to existing directory {str(venv_dir)!r}. "
+            print(
+                f"{package!r} already seems to be installed. "
+                "Not modifying existing installation in {str(venv_dir)!r}. "
                 "Pass '--force' to force installation"
             )
+            return
 
     venv = Venv(venv_dir, python=python, verbose=verbose)
     venv.create_venv(venv_args, pip_args)

tests/test_pipx.py

@@ -166,6 +166,10 @@ def test_editable_install(self):
             [self.pipx_bin, "install", "-e", "pipx", "--spec", PIPX_PATH], check=True
         )
 
+    def test_install_existing_package(self):
+        subprocess.run([self.pipx_bin, "install", "pycowsay"], check=True)
+        subprocess.run([self.pipx_bin, "install", "pycowsay"], check=True)
+
     def test_runpip(self):
         subprocess.run([self.pipx_bin, "install", "pycowsay"], check=True)
         subprocess.run([self.pipx_bin, "runpip", "pycowsay", "list"], check=True)