providers/docker: can set default provider to docker [GH-3662]

CHANGELOG.md

@@ -13,6 +13,8 @@ BUG FIXES:
   - guests/redhat: Fix networking issues with CentOS. [GH-3649]
   - guests/windows: Human error if WinRM not in use to configure networks. [GH-3651]
   - providers/docker: Show proper error message when on Linux. [GH-3654]
+  - providers/docker: Proxy VM works properly even if default provider
+      environmental variable set to "docker" [GH-3662]
   - synced\_folders/rsync: Create the directory before syncing.
 
 ## 1.6.0 (May 6, 2014)

plugins/providers/docker/provider.rb

@@ -87,7 +87,10 @@ module VagrantPlugins
 
           host_env.machine(
             host_machine_name,
-            host_env.default_provider(exclude: [:docker]))
+            host_env.default_provider(
+              exclude: [:docker],
+              force_default: false,
+            ))
         end
 
         @host_vm

test/unit/vagrant/environment_test.rb

@@ -766,6 +766,27 @@ VF
       end
     end
 
+    it "prefers the default even if not forced" do
+      plugin_providers[:baz] = [provider_usable_class(true), { priority: 5 }]
+      plugin_providers[:foo] = [provider_usable_class(true), { priority: 5 }]
+      plugin_providers[:bar] = [provider_usable_class(true), { priority: 7 }]
+
+      with_temp_env("VAGRANT_DEFAULT_PROVIDER" => "baz") do
+        expect(subject.default_provider(force_default: false)).to eq(:baz)
+      end
+    end
+
+    it "uses the first usable provider that isn't the default if excluded" do
+      plugin_providers[:foo] = [provider_usable_class(true), { priority: 5 }]
+      plugin_providers[:bar] = [provider_usable_class(true), { priority: 7 }]
+      plugin_providers[:baz] = [provider_usable_class(true), { priority: 8 }]
+
+      with_temp_env("VAGRANT_DEFAULT_PROVIDER" => "baz") do
+        expect(subject.default_provider(
+          exclude: [:baz], force_default: false)).to eq(:bar)
+      end
+    end
+
     it "is VirtualBox if nothing else is usable" do
       plugin_providers[:foo] = [provider_usable_class(false), { priority: 5 }]
       plugin_providers[:bar] = [provider_usable_class(false), { priority: 5 }]