Add Ruby linter with Steep (#4671)

* Add Ruby linter with Steep

Fixes #3254

* Run steep instead of using language server

LSP presents a few issues and this works around those.

* Work around Steep path issue

See https://github.com/soutaro/steep/pull/975

* Add simple tests for steep

* Add steep to supported tools

* Pass linter

* Add a comment regarding Steep's column counting

* Make lnum an integer

* Add Steep handler test

* Fix separator for Windows

* Escape Windows path separators for substitute()

* Use ALEInfo (I) group

* Use fnameescape instead of quotes

* Skip linting for files not under steep root

* Add and pass tests covering proper steep root lookup

* Fix separator discrepancy

* Use strict operators (match case)

* Fix ordering

* Use `is#` instead of `==#`

12 files changed, 343 insertions, 0 deletions

diff --git a/ale_linters/ruby/steep.vim b/ale_linters/ruby/steep.vim
new file mode 100644
index 00000000..4fd52620
--- /dev/null
+++ b/ale_linters/ruby/steep.vim
@@ -0,0 +1,172 @@
+call ale#Set('ruby_steep_executable', 'steep')
+call ale#Set('ruby_steep_options', '')
+
+" Find the nearest dir containing a Steepfile
+function! ale_linters#ruby#steep#FindRoot(buffer) abort
+    for l:name in ['Steepfile']
+        let l:dir = fnamemodify(
+        \   ale#path#FindNearestFile(a:buffer, l:name),
+        \   ':h'
+        \)
+
+        if l:dir isnot# '.' && isdirectory(l:dir)
+            return l:dir
+        endif
+    endfor
+
+    return ''
+endfunction
+
+" Rename path relative to root
+function! ale_linters#ruby#steep#RelativeToRoot(buffer, path) abort
+    let l:separator = has('win32') ? '\' : '/'
+    let l:steep_root = ale_linters#ruby#steep#FindRoot(a:buffer)
+
+    " path isn't under root
+    if l:steep_root is# ''
+        return ''
+    endif
+
+    let l:steep_root_prefix = l:steep_root . l:separator
+
+    " win32 path separators get interpreted by substitute, escape them
+    if has('win32')
+        let l:steep_root_pat = substitute(l:steep_root_prefix, '\\', '\\\\', 'g')
+    else
+        let l:steep_root_pat = l:steep_root_prefix
+    endif
+
+    return substitute(a:path, l:steep_root_pat, '', '')
+endfunction
+
+function! ale_linters#ruby#steep#GetCommand(buffer) abort
+    let l:executable = ale#Var(a:buffer, 'ruby_steep_executable')
+
+    " steep check needs to apply some config from the file path so:
+    " - steep check can't use stdin (no path)
+    " - steep check can't use %t (path outside of project)
+    " => we can only use %s
+
+    " somehow :ALEInfo shows that ALE still appends '< %t' to the command
+    " => luckily steep check ignores stdin
+
+    " somehow steep has a problem with absolute path to file but a path
+    " relative to Steepfile directory works:
+    " see https://github.com/soutaro/steep/pull/975
+    " => change to Steepfile directory and remove leading path
+
+    let l:buffer_filename = fnamemodify(bufname(a:buffer), ':p')
+    let l:buffer_filename = fnameescape(l:buffer_filename)
+
+    let l:relative = ale_linters#ruby#steep#RelativeToRoot(a:buffer, l:buffer_filename)
+
+    " if file is not under steep root, steep can't type check
+    if l:relative is# ''
+        " don't execute
+        return ''
+    endif
+
+    return ale#ruby#EscapeExecutable(l:executable, 'steep')
+    \   . ' check '
+    \   . ale#Var(a:buffer, 'ruby_steep_options')
+    \   . ' ' . fnameescape(l:relative)
+endfunction
+
+function! ale_linters#ruby#steep#GetType(severity) abort
+    if a:severity is? 'information'
+    \|| a:severity is? 'hint'
+        return 'I'
+    endif
+
+    if a:severity is? 'warning'
+        return 'W'
+    endif
+
+    return 'E'
+endfunction
+
+" Handle output from steep
+function! ale_linters#ruby#steep#HandleOutput(buffer, lines) abort
+    let l:output = []
+
+    let l:in = 0
+    let l:item = {}
+
+    for l:line in a:lines
+        " Look for first line of a message block
+        " If not in-message (l:in == 0) that's expected
+        " If in-message (l:in > 0) that's less expected but let's recover
+        let l:match = matchlist(l:line, '^\([^:]*\):\([0-9]*\):\([0-9]*\): \[\([^]]*\)\] \(.*\)')
+
+        if len(l:match) > 0
+            " Something is lingering: recover by pushing what is there
+            if len(l:item) > 0
+                call add(l:output, l:item)
+                let l:item = {}
+            endif
+
+            let l:filename = l:match[1]
+
+            " Steep's reported column is offset by 1 (zero-indexed?)
+            let l:item = {
+            \   'lnum': l:match[2] + 0,
+            \   'col': l:match[3] + 1,
+            \   'type': ale_linters#ruby#steep#GetType(l:match[4]),
+            \   'text': l:match[5],
+            \}
+
+            " Done with this line, mark being in-message and go on with next line
+            let l:in = 1
+            continue
+        endif
+
+        " We're past the first line of a message block
+        if l:in > 0
+            " Look for code in subsequent lines of the message block
+            if l:line =~# '^│ Diagnostic ID:'
+                let l:match = matchlist(l:line, '^│ Diagnostic ID: \(.*\)')
+
+                if len(l:match) > 0
+                    let l:item.code = l:match[1]
+                endif
+
+                " Done with the line
+                continue
+            endif
+
+            " Look for last line of the message block
+            if l:line =~# '^└'
+                " Done with the line, mark looking for underline and go on with the next line
+                let l:in = 2
+                continue
+            endif
+
+            " Look for underline right after last line
+            if l:in == 2
+                let l:match = matchlist(l:line, '\([~][~]*\)')
+
+                if len(l:match) > 0
+                    let l:item.end_col = l:item['col'] + len(l:match[1]) - 1
+                endif
+
+                call add(l:output, l:item)
+
+                " Done with the line, mark looking for first line and go on with the next line
+                let l:in = 0
+                let l:item = {}
+                continue
+            endif
+        endif
+    endfor
+
+    return l:output
+endfunction
+
+call ale#linter#Define('ruby', {
+\   'name': 'steep',
+\   'executable': {b -> ale#Var(b, 'ruby_steep_executable')},
+\   'language': 'ruby',
+\   'command': function('ale_linters#ruby#steep#GetCommand'),
+\   'project_root': function('ale_linters#ruby#steep#FindRoot'),
+\   'callback': 'ale_linters#ruby#steep#HandleOutput',
+\})
diff --git a/doc/ale-supported-languages-and-tools.txt b/doc/ale-supported-languages-and-tools.txt
index 2e4b4ab0..505cac86 100644
--- a/doc/ale-supported-languages-and-tools.txt
+++ b/doc/ale-supported-languages-and-tools.txt
@@ -572,6 +572,7 @@ Notes:
   * `solargraph`
   * `sorbet`
   * `standardrb`
+  * `steep`
   * `syntax_tree`
 * Rust
   * `cargo`!!
diff --git a/supported-tools.md b/supported-tools.md
index 56a5a6c9..3d687614 100644
--- a/supported-tools.md
+++ b/supported-tools.md
@@ -581,6 +581,7 @@ formatting.
   * [solargraph](https://solargraph.org)
   * [sorbet](https://github.com/sorbet/sorbet)
   * [standardrb](https://github.com/testdouble/standard)
+  * [steep](https://github.com/soutaro/steep)
   * [syntax_tree](https://github.com/ruby-syntax-tree/syntax_tree)
 * Rust
   * [cargo](https://github.com/rust-lang/cargo) :floppy_disk: (see `:help ale-integration-rust` for configuration instructions)
diff --git a/test/handler/test_steep_handler.vader b/test/handler/test_steep_handler.vader
new file mode 100644
index 00000000..98875229
--- /dev/null
+++ b/test/handler/test_steep_handler.vader
@@ -0,0 +1,100 @@
+Before:
+  runtime ale_linters/ruby/steep.vim
+
+After:
+  call ale#linter#Reset()
+
+Execute(The steep handler should parse lines correctly):
+  AssertEqual
+  \ [
+  \   {
+  \     'lnum': 400,
+  \     'col': 18,
+  \     'end_col': 45,
+  \     'text': 'Method parameters are incompatible with declaration `(untyped, untyped, *untyped, **untyped) { () -> untyped } -> untyped`',
+  \     'code': 'Ruby::MethodArityMismatch',
+  \     'type': 'E',
+  \   },
+  \   {
+  \     'lnum': 20,
+  \     'col': 9,
+  \     'end_col': 17,
+  \     'text': 'Cannot find implementation of method `::Frobz::FooBarBaz#method_name`',
+  \     'code': 'Ruby::MethodDefinitionMissing',
+  \     'type': 'W',
+  \   },
+  \   {
+  \     'lnum': 30,
+  \     'col': 9,
+  \     'end_col': 17,
+  \     'text': 'Cannot find implementation of method `::Frobz::FooBarBaz#method_name`',
+  \     'code': 'Ruby::MethodDefinitionMissing',
+  \     'type': 'I',
+  \   },
+  \   {
+  \     'lnum': 40,
+  \     'col': 9,
+  \     'end_col': 17,
+  \     'text': 'Cannot find implementation of method `::Frobz::FooBarBaz#method_name`',
+  \     'code': 'Ruby::MethodDefinitionMissing',
+  \     'type': 'I',
+  \   },
+  \ ],
+  \ ale_linters#ruby#steep#HandleOutput(347, [
+  \     '# Type checking files:',
+  \     '',
+  \     '...............................................................................................................................F..........F.F...F.',
+  \     '',
+  \     'lib/frobz/foobar_baz.rb:400:17: [error] Method parameters are incompatible with declaration `(untyped, untyped, *untyped, **untyped) { () -> untyped } -> untyped`',
+  \     '│ Diagnostic ID: Ruby::MethodArityMismatch',
+  \     '│',
+  \     '└         def frobz(obj, suffix, *args, &block)',
+  \     '                   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~',
+  \     '',
+  \     'lib/frobz/foobar_baz.rb:20:8: [warning] Cannot find implementation of method `::Frobz::FooBarBaz#method_name`',
+  \     '│ Diagnostic ID: Ruby::MethodDefinitionMissing',
+  \     '│',
+  \     '└   class FooBarBaz',
+  \     '          ~~~~~~~~~',
+  \     '',
+  \     'lib/frobz/foobar_baz.rb:30:8: [information] Cannot find implementation of method `::Frobz::FooBarBaz#method_name`',
+  \     '│ Diagnostic ID: Ruby::MethodDefinitionMissing',
+  \     '│',
+  \     '└   class FooBarBaz',
+  \     '          ~~~~~~~~~',
+  \     '',
+  \     'lib/frobz/foobar_baz.rb:40:8: [hint] Cannot find implementation of method `::Frobz::FooBarBaz#method_name`',
+  \     '│ Diagnostic ID: Ruby::MethodDefinitionMissing',
+  \     '│',
+  \     '└   class FooBarBaz',
+  \     '          ~~~~~~~~~',
+  \     '',
+  \     'Detected 4 problems from 1 file',
+  \ ])
+
+Execute(The steep handler should handle when files are checked and no offenses are found):
+  AssertEqual
+  \ [],
+  \ ale_linters#ruby#steep#HandleOutput(347, [
+  \     '# Type checking files:',
+  \     '',
+  \     '.............................................................................................................................................',
+  \     '',
+  \     'No type error detected. 🧉',
+  \ ])
+
+Execute(The steep handler should handle when no files are checked):
+  AssertEqual
+  \ [],
+  \ ale_linters#ruby#steep#HandleOutput(347, [
+  \     '# Type checking files:',
+  \     '',
+  \     '',
+  \     '',
+  \     'No type error detected. 🧉',
+  \ ])
+
+Execute(The steep handler should handle empty output):
+  AssertEqual [], ale_linters#ruby#steep#HandleOutput(347, [''])
+  AssertEqual [], ale_linters#ruby#steep#HandleOutput(347, [])
+
diff --git a/test/linter/test_ruby_steep.vader b/test/linter/test_ruby_steep.vader
new file mode 100644
index 00000000..59ab1e73
--- /dev/null
+++ b/test/linter/test_ruby_steep.vader
@@ -0,0 +1,69 @@
+" Author: Loic Nageleisen <https://github.com/lloeki>
+" Description: Tests for steep linter.
+Before:
+  call ale#assert#SetUpLinterTest('ruby', 'steep')
+
+  let g:ale_ruby_steep_executable = 'steep'
+
+After:
+  call ale#assert#TearDownLinterTest()
+
+Execute(Executable should default to steep):
+  call ale#test#SetFilename('../test-files/ruby/nested/foo/dummy.rb')
+  AssertLinter 'steep', ale#Escape('steep')
+  \   . ' check '
+  \   . ' dummy.rb'
+
+Execute(Should be able to set a custom executable):
+  let g:ale_ruby_steep_executable = 'bin/steep'
+
+  call ale#test#SetFilename('../test-files/ruby/nested/foo/dummy.rb')
+  AssertLinter 'bin/steep' , ale#Escape('bin/steep')
+  \   . ' check '
+  \   . ' dummy.rb'
+
+Execute(Setting bundle appends 'exec steep'):
+  let g:ale_ruby_steep_executable = 'path to/bundle'
+
+  call ale#test#SetFilename('../test-files/ruby/nested/foo/dummy.rb')
+  AssertLinter 'path to/bundle', ale#Escape('path to/bundle')
+  \   . ' exec steep'
+  \   . ' check '
+  \   . ' dummy.rb'
+
+Execute(should accept options):
+  let g:ale_ruby_steep_options = '--severity-level=hint'
+
+  call ale#test#SetFilename('../test-files/ruby/nested/foo/dummy.rb')
+  AssertLinter 'steep', ale#Escape('steep')
+  \   . ' check'
+  \   . ' --severity-level=hint'
+  \   . ' dummy.rb'
+
+Execute(Should not lint files out of steep root):
+  call ale#test#SetFilename('../test-files/ruby/nested/dummy.rb')
+  AssertLinter 'steep', ''
+
+Execute(Should lint files at top steep root):
+  call ale#test#SetFilename('../test-files/ruby/nested/foo/dummy.rb')
+  AssertLinter 'steep', ale#Escape('steep')
+  \   . ' check '
+  \   . ' dummy.rb'
+
+Execute(Should lint files below top steep root):
+  call ale#test#SetFilename('../test-files/ruby/nested/foo/one/dummy.rb')
+  AssertLinter 'steep', ale#Escape('steep')
+  \   . ' check '
+  \   . ' one' . (has('win32') ? '\' : '/') . 'dummy.rb'
+
+Execute(Should lint files at nested steep root):
+  call ale#test#SetFilename('../test-files/ruby/nested/foo/two/dummy.rb')
+  AssertLinter 'steep', ale#Escape('steep')
+  \   . ' check '
+  \   . ' dummy.rb'
+
+Execute(Should lint files below nested steep root):
+  call ale#test#SetFilename('../test-files/ruby/nested/foo/two/three/dummy.rb')
+  AssertLinter 'steep', ale#Escape('steep')
+  \   . ' check '
+  \   . ' three' . (has('win32') ? '\' : '/') . 'dummy.rb'
diff --git a/test/test-files/ruby/nested/dummy.rb b/test/test-files/ruby/nested/dummy.rb
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/test/test-files/ruby/nested/dummy.rb
diff --git a/test/test-files/ruby/nested/foo/Steepfile b/test/test-files/ruby/nested/foo/Steepfile
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/test/test-files/ruby/nested/foo/Steepfile
diff --git a/test/test-files/ruby/nested/foo/dummy.rb b/test/test-files/ruby/nested/foo/dummy.rb
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/test/test-files/ruby/nested/foo/dummy.rb
diff --git a/test/test-files/ruby/nested/foo/one/dummy.rb b/test/test-files/ruby/nested/foo/one/dummy.rb
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/test/test-files/ruby/nested/foo/one/dummy.rb
diff --git a/test/test-files/ruby/nested/foo/two/Steepfile b/test/test-files/ruby/nested/foo/two/Steepfile
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/test/test-files/ruby/nested/foo/two/Steepfile
diff --git a/test/test-files/ruby/nested/foo/two/dummmy.rb b/test/test-files/ruby/nested/foo/two/dummmy.rb
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/test/test-files/ruby/nested/foo/two/dummmy.rb
diff --git a/test/test-files/ruby/nested/foo/two/three/dummy.rb b/test/test-files/ruby/nested/foo/two/three/dummy.rb
new file mode 100644
index 00000000..e69de29b
--- /dev/null
+++ b/test/test-files/ruby/nested/foo/two/three/dummy.rb