Prefer project root containing vendor directory

Previously when setting b:composer_root, the closest composer.json would
be used. Now, the closest composer.json with sibling vendor/autoload.php
is used. If none is found, falls back to the closest composer.json.

The rationale is that it is not useful to scope :Composer and the
navigation commands (:Ecomposer et al.) to an installed dependency, and
<Plug>(composer-find) was broken when jumping from a dependency.

Fixes #5.

Author: noahfrederick

plugin/composer.vim

@@ -62,7 +62,8 @@ let g:loaded_composer = 1
 " Detection {{{
 
 ""
-" Determine whether the current or supplied [path] belongs to a Composer project
+" Determine whether the current or supplied [path] belongs to a Composer
+" project, and set b:composer_root to the path of the project root.
 function! s:composer_detect(...) abort
   if exists('b:composer_root')
     return 1
@@ -74,10 +75,19 @@ function! s:composer_detect(...) abort
     let fn = fnamemodify(fn, ':h')
   endif
 
-  let composer_json = findfile('composer.json', escape(fn, ', ') . ';')
+  let candidates = findfile('composer.json', escape(fn, ', ') . ';', -1)
 
-  if !empty(composer_json)
-    let b:composer_root = fnamemodify(composer_json, ':p:h')
+  for json in candidates
+    let root = fnamemodify(json, ':p:h')
+
+    if filereadable(root.'/vendor/autoload.php')
+      let b:composer_root = root
+      return 1
+    endif
+  endfor
+
+  if !empty(candidates)
+    let b:composer_root = fnamemodify(candidates[0], ':p:h')
     return 1
   endif
 endfunction

t/activation.vim

@@ -37,6 +37,22 @@ describe 's:composer_detect()'
       Expect b:composer_root == g:fixtures . 'project-composer'
     end
   end
+
+  context 'in a dependency of a composer project'
+    it 'sets b:composer_root to the root project'
+      execute 'edit' g:fixtures . 'project-composer/vendor/foo/bar/index.php'
+      Expect exists('b:composer_root') to_be_true
+      Expect b:composer_root == g:fixtures . 'project-composer'
+    end
+  end
+
+  context 'in a composer project without a vendor autoload'
+    it 'sets b:composer_root'
+      execute 'edit' g:fixtures . 'project-uninstalled/index.php'
+      Expect exists('b:composer_root') to_be_true
+      Expect b:composer_root == g:fixtures . 'project-uninstalled'
+    end
+  end
 end
 
 describe 'composer#buffer_setup()'

t/fixtures/project-composer/vendor/autoload.php

@@ -0,0 +1,3 @@
+<?php
+
+// Dummy PHP file

t/fixtures/project-composer/vendor/foo/bar/composer.json

@@ -0,0 +1,3 @@
+<?php
+
+// Dummy PHP file

t/fixtures/project-composer/vendor/foo/bar/index.php

@@ -0,0 +1,3 @@
+<?php
+
+// Dummy PHP file

t/fixtures/project-phar/vendor/autoload.php

@@ -0,0 +1,3 @@
+<?php
+
+// Dummy PHP file

t/fixtures/project-phar/vendor/foo/bar/composer.json

@@ -0,0 +1,3 @@
+<?php
+
+// Dummy PHP file