Add cucumber checker for cucumber files

For now, it only detects undefined steps. The nearest `features` dir
above the buffer file is loaded, so step definitions should be found
correctly.

Tested only with Cucumber for Ruby, but it should work for any cucumber
that follows a substantially similar directory structure.

1 files changed, 45 insertions, 0 deletions

diff --git a/ale_linters/cucumber/cucumber.vim b/ale_linters/cucumber/cucumber.vim
new file mode 100644
index 00000000..6708d32f
--- /dev/null
+++ b/ale_linters/cucumber/cucumber.vim
@@ -0,0 +1,45 @@
+" Author: Eddie Lebow https://github.com/elebow
+" Description: Cucumber, a BDD test tool
+
+function! ale_linters#cucumber#cucumber#GetCommand(buffer) abort
+    let l:features_dir = ale#path#FindNearestDirectory(a:buffer, 'features')
+
+    if !empty(l:features_dir)
+        let l:features_arg = '-r ' . ale#Escape(l:features_dir)
+    else
+        let l:features_arg = ''
+    endif
+
+    return 'cucumber --dry-run --quiet --strict --format=json '
+    \   . l:features_arg . ' %t'
+endfunction
+
+function! ale_linters#cucumber#cucumber#Handle(buffer, lines) abort
+    try
+        let l:json = ale#util#FuzzyJSONDecode(a:lines, {})[0]
+    catch
+        return []
+    endtry
+
+    let l:output = []
+    for l:element in get(l:json, 'elements', [])
+        for l:step in l:element['steps']
+            if l:step['result']['status'] is# 'undefined'
+                call add(l:output, {
+                \   'lnum': l:step['line'],
+                \   'code': 'E',
+                \   'text': 'Undefined step'
+                \})
+            endif
+        endfor
+    endfor
+
+    return l:output
+endfunction
+
+call ale#linter#Define('cucumber', {
+\   'name': 'cucumber',
+\   'executable': 'cucumber',
+\   'command_callback': 'ale_linters#cucumber#cucumber#GetCommand',
+\   'callback': 'ale_linters#cucumber#cucumber#Handle'
+\})