Added functionality to set flag_value correctly when using envvar (#2788

)

Co-authored-by: Andreas Backx <[email protected]>

CHANGES.rst

@@ -51,6 +51,9 @@ Unreleased
 -   Add ``ProgressBar(hidden: bool)`` to allow hiding the progressbar. :issue:`2609`
 -   A ``UserWarning`` will be shown when multiple parameters attempt to use the
     same name. :issue:`2396``
+-   When using ``Option.envvar`` with ``Option.flag_value``, the ``flag_value``
+    will always be used instead of the value of the environment variable.
+    :issue:`2746` :pr:`2788`
 
 
 Version 8.1.8

src/click/core.py

@@ -2430,15 +2430,19 @@ class Option(Parameter):
     :param hidden: hide this option from help outputs.
     :param attrs: Other command arguments described in :class:`Parameter`.
 
-    .. versionchanged:: 8.1.0
+    .. versionchanged:: 8.2
+        ``envvar`` used with ``flag_value`` will always use the ``flag_value``,
+        previously it would use the value of the environment variable.
+
+    .. versionchanged:: 8.1
         Help text indentation is cleaned here instead of only in the
         ``@option`` decorator.
 
-    .. versionchanged:: 8.1.0
+    .. versionchanged:: 8.1
         The ``show_default`` parameter overrides
         ``Context.show_default``.
 
-    .. versionchanged:: 8.1.0
+    .. versionchanged:: 8.1
         The default of a single option boolean flag is not shown if the
         default value is ``False``.
 
@@ -2864,6 +2868,8 @@ def resolve_envvar_value(self, ctx: Context) -> str | None:
         rv = super().resolve_envvar_value(ctx)
 
         if rv is not None:
+            if self.is_flag and self.flag_value:
+                return str(self.flag_value)
             return rv
 
         if (

tests/test_arguments.py

@@ -198,6 +198,19 @@ def cmd(arg):
         assert result.return_value == expect
 
 
+def test_envvar_flag_value(runner):
+    @click.command()
+    # is_flag is implicitly true
+    @click.option("--upper", flag_value="upper", envvar="UPPER")
+    def cmd(upper):
+        click.echo(upper)
+        return upper
+
+    # For whatever value of the `env` variable, if it exists, the flag should be `upper`
+    result = runner.invoke(cmd, env={"UPPER": "whatever"})
+    assert result.output.strip() == "upper"
+
+
 def test_nargs_envvar_only_if_values_empty(runner):
     @click.command()
     @click.argument("arg", envvar="X", nargs=-1)