Align the credential_store false vocabulary with to_bool

`credential_store` was the only Bundler setting that read `off` as
disabled, while every other setting goes through `Settings#to_bool`,
whose false vocabulary has never had it. The disabled branch now
delegates to `#to_bool` so the two cannot drift again. The true list
stays because the setting is tri-state and the boolean spellings still
have to be told apart from a backend name.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: hsbt

lib/bundler/man/bundle-config.1

@@ -107,6 +107,8 @@ A \fBcreated_at\fR timestamp is read as UTC when it carries no time zone offset\
 .IP "\(bu" 4
 \fBcredential_store\fR (\fBBUNDLE_CREDENTIAL_STORE\fR): Experimental: store and read host credentials (the values otherwise set via \fBbundle config set <host> <user:pass>\fR) in a credential store instead of the plain text config file\. Set it to \fBtrue\fR to use the operating system's native store (macOS Keychain, Linux Secret Service, Windows Credential Manager) when one is available on this platform, or to the name of a backend provided by a third\-party gem, such as \fB1password\fR\. Falls back to the config file when the store is unavailable or fails, warning that the credential was written in plain text\. Defaults to false\. Credentials already written to the config file are not migrated automatically; re\-run \fBbundle config set <host> <user:pass>\fR with the setting enabled to move each one into the store\. Being experimental, the name and behavior of this setting may change in a future release\.
 .IP
+The value is read in three ways\. An empty value and the false values Bundler takes everywhere else (\fBfalse\fR, \fBf\fR, \fBno\fR, \fBn\fR, \fB0\fR) turn the store off\. \fBtrue\fR, \fBt\fR, \fByes\fR, \fBy\fR, \fBon\fR and \fB1\fR select the native store\. Case does not matter for any of those\. Anything else is a backend name, taken as written, and only lowercase letters, digits, \fB_\fR and \fB\-\fR are recognized in one\. So \fBoff\fR names a backend rather than turning the store off, which \fBfalse\fR does\.
+.IP
 A credential kept in the store is never printed back\. \fBbundle config get <host>\fR and \fBbundle config list\fR name the key and say that its value lives in the credential store\. With \fB\-\-parseable\fR, such a key is left out entirely, since that output is meant to be read back by \fBbundle config set\fR\. A third\-party backend is not required to enumerate what it holds, so a credential kept in one may not be listed at all\.
 .IP
 The store belongs to the machine's user, not to a project, so \fB\-\-local\fR and \fB\-\-global\fR make no difference to where a credential is kept\. Setting a host's credential in one project changes it for every project on the machine, and unsetting it there removes it everywhere\. Protecting the store itself is the operating system's job, or that of whichever backend you selected\.

lib/bundler/man/bundle-config.1.ronn

@@ -193,6 +193,14 @@ learn more about their operation in [bundle install(1)](bundle-install.1.html).
    setting enabled to move each one into the store. Being experimental, the
    name and behavior of this setting may change in a future release.
 
+   The value is read in three ways. An empty value and the false values
+   Bundler takes everywhere else (`false`, `f`, `no`, `n`, `0`) turn the
+   store off. `true`, `t`, `yes`, `y`, `on` and `1` select the native store.
+   Case does not matter for any of those. Anything else is a backend name,
+   taken as written, and only lowercase letters, digits, `_` and `-` are
+   recognized in one. So `off` names a backend rather than turning the store
+   off, which `false` does.
+
    A credential kept in the store is never printed back. `bundle config get
    <host>` and `bundle config list` name the key and say that its value lives
    in the credential store. With `--parseable`, such a key is left out

lib/bundler/settings.rb

@@ -465,17 +465,16 @@ def is_userinfo(value)
       value.include?(":")
     end
 
-    ##
-    # The Gem::CredentialStore instance to use, or nil when the
-    # `credential_store` setting is off. The value is `true`/`"true"` for this
-    # platform's native backend or a backend name such as `"1password"`.
-    # Guarded by a cheap lookup so reading and writing settings costs nothing
-    # extra when the setting is disabled.
-
     # Kept separate from RubyGems so gem signout does not remove Bundler's
     # host credentials.
     CREDENTIAL_STORE_SERVICE = "bundler"
 
+    ##
+    # The Gem::CredentialStore for the spec #credential_store_spec returns,
+    # or nil when the setting is off or this RubyGems has no credential store.
+    # Guarded by a cheap lookup so reading and writing settings costs nothing
+    # extra when the setting is disabled.
+
     def active_credential_store(host = nil)
       spec = credential_store_spec(host)
       return nil unless spec
@@ -493,8 +492,13 @@ def credential_store_spec(host = nil)
       value = self[:credential_store] if value.nil?
 
       # An environment variable can carry bytes String#downcase would reject.
-      case value.to_s.b.downcase
-      when "", "false", "0", "no", "off", "f", "n" then nil
+      normalized = value.to_s.b.downcase
+
+      # Tri-state, unlike a BOOL_KEYS setting, so #to_bool is only consulted
+      # for the false half.
+      return nil unless to_bool(normalized)
+
+      case normalized
       when "true", "1", "yes", "on", "t", "y" then true
       else value.to_s
       end

spec/bundler/settings_spec.rb

@@ -275,6 +275,53 @@
     end
   end
 
+  describe "#credential_store_spec" do
+    it "is off when the setting is unset" do
+      expect(settings.send(:credential_store_spec)).to be_nil
+    end
+
+    it "reads the same false spellings as every other Bundler boolean" do
+      ["", "false", "FALSE", "f", "no", "n", "0"].each do |off|
+        settings.set_local "credential_store", off
+
+        expect(settings.send(:credential_store_spec)).to be_nil, "#{off.inspect} should turn the store off"
+      end
+    end
+
+    it "reads the boolean true spellings as this platform's native store" do
+      %w[true TRUE t yes y on 1].each do |on|
+        settings.set_local "credential_store", on
+
+        expect(settings.send(:credential_store_spec)).to be(true), "#{on.inspect} should select the native store"
+      end
+    end
+
+    it "reads anything else as a backend name, `off` included" do
+      %w[1password off 1Password].each do |name|
+        settings.set_local "credential_store", name
+
+        expect(settings.send(:credential_store_spec)).to eq(name)
+      end
+    end
+
+    it "lets a host override the global setting" do
+      settings.set_local "credential_store", "1password"
+      settings.set_local "credential_store.gemserver.example.org", "false"
+
+      expect(settings.send(:credential_store_spec, "gemserver.example.org")).to be_nil
+      expect(settings.send(:credential_store_spec, "other.example.org")).to eq("1password")
+    end
+
+    it "survives an undecodable environment variable" do
+      # #to_bool refuses these bytes too, not just String#downcase.
+      without_env_side_effects do
+        ENV["BUNDLE_CREDENTIAL_STORE"] = "\xff".dup.force_encoding("UTF-8")
+
+        expect(settings.send(:credential_store_spec)).to eq(ENV["BUNDLE_CREDENTIAL_STORE"])
+      end
+    end
+  end
+
   describe "#credentials_for" do
     let(:uri) { Gem::URI("https://gemserver.example.org/") }
     let(:credentials) { "username:password" }