Respect VIRTUAL_ENV_DISABLE_PROMPT in nushell activation script (#2458)

Fixes #2461

Author: m-lima

docs/changelog/2461.bugfix.rst

@@ -0,0 +1 @@
+Make ``activate.nu`` respect ``VIRTUAL_ENV_DISABLE_PROMPT`` and not set the prompt if reqeusted - by :user:`m-lima`.

src/virtualenv/activation/nushell/activate.nu

@@ -15,6 +15,21 @@ export-env {
         $name in (env).name
     }
 
+    # Emulates a `test -z`, but btter as it handles e.g 'false'
+    def is-env-true [name: string] {
+      if (has-env $name) {
+        # Try to parse 'true', '0', '1', and fail if not convertible
+        let parsed = do -i { $env | get $name | into bool }
+        if ($parsed | describe) == 'bool' {
+          $parsed
+        } else {
+          not ($env | get $name | is-empty)
+        }
+      } else {
+        false
+      }
+    }
+
     let is_windows = ($nu.os-info.name | str downcase) == 'windows'
     let virtual_env = '__VIRTUAL_ENV__'
     let bin = '__BIN_NAME__'
@@ -49,44 +64,53 @@ export-env {
     let venv_path = ([$virtual_env $bin] | path join)
     let new_path = ($old_path | prepend $venv_path | str collect $path_sep)
 
-    # Creating the new prompt for the session
-    let virtual_prompt = if ('__VIRTUAL_PROMPT__' == '') {
-        $'(char lparen)($virtual_env | path basename)(char rparen) '
-    } else {
-        '(__VIRTUAL_PROMPT__) '
+    let new_env = {
+        $path_name  : $new_path
+        VIRTUAL_ENV : $virtual_env
     }
 
-    # Back up the old prompt builder
-    let old_prompt_command = if (has-env 'VIRTUAL_ENV') and (has-env '_OLD_PROMPT_COMMAND') {
-        $env._OLD_PROMPT_COMMAND
+    let new_env = if (is-env-true 'VIRTUAL_ENV_DISABLE_PROMPT') {
+      $new_env
     } else {
-        if (has-env 'PROMPT_COMMAND') {
-            $env.PROMPT_COMMAND
-        } else {
-            ''
-        }
-    }
+      # Creating the new prompt for the session
+      let virtual_prompt = if ('__VIRTUAL_PROMPT__' == '') {
+          $'(char lparen)($virtual_env | path basename)(char rparen) '
+      } else {
+          '(__VIRTUAL_PROMPT__) '
+      }
 
-    # If there is no default prompt, then only the env is printed in the prompt
-    let new_prompt = if (has-env 'PROMPT_COMMAND') {
-        if ($old_prompt_command | describe) == 'block' {
-            { $'($virtual_prompt)(do $old_prompt_command)' }
-        } else {
-            { $'($virtual_prompt)($old_prompt_command)' }
-        }
-    } else {
-        { $'($virtual_prompt)' }
-    }
+      # Back up the old prompt builder
+      let old_prompt_command = if (has-env 'VIRTUAL_ENV') and (has-env '_OLD_PROMPT_COMMAND') {
+          $env._OLD_PROMPT_COMMAND
+      } else {
+          if (has-env 'PROMPT_COMMAND') {
+              $env.PROMPT_COMMAND
+          } else {
+              ''
+          }
+      }
 
-    # Environment variables that will be loaded as the virtual env
-    load-env {
-        $path_name          : $new_path
-        VIRTUAL_ENV         : $virtual_env
+      # If there is no default prompt, then only the env is printed in the prompt
+      let new_prompt = if (has-env 'PROMPT_COMMAND') {
+          if ($old_prompt_command | describe) == 'block' {
+              { $'($virtual_prompt)(do $old_prompt_command)' }
+          } else {
+              { $'($virtual_prompt)($old_prompt_command)' }
+          }
+      } else {
+          { $'($virtual_prompt)' }
+      }
+
+      $new_env | merge {
         _OLD_VIRTUAL_PATH   : ($old_path | str collect $path_sep)
         _OLD_PROMPT_COMMAND : $old_prompt_command
         PROMPT_COMMAND      : $new_prompt
         VIRTUAL_PROMPT      : $virtual_prompt
+      }
     }
+
+    # Environment variables that will be loaded as the virtual env
+    load-env $new_env
 }
 
 export alias pydoc = python -m pydoc