Add fsc linter for Scala (#1452)

* Add fsc as a Scala linter

* Pull reused code into `autoload/ale/` directory

* Include fsc into the README

* Add unit test for testing the scala handler

* Add unit test for scala's fsc linter

* Rename scala unit tests for clarity

* Fix typo in README

* Fix typos in doc/ale.txt

* Fix author headline

* Put methods for fsc commands back into fsc.vim

* Move command_callback tests to correct location

* Rewrite handler test so it actually tests handler

* Clarify description of test in test_scala_handler

8 files changed, 120 insertions, 41 deletions

diff --git a/README.md b/README.md
index 926c209a..b5dd0e9d 100644
--- a/README.md
+++ b/README.md
@@ -150,7 +150,7 @@ formatting.
 | Rust |  cargo !! (see `:help ale-integration-rust` for configuration instructions), [rls](https://github.com/rust-lang-nursery/rls), [rustc](https://www.rust-lang.org/), [rustfmt](https://github.com/rust-lang-nursery/rustfmt) |
 | SASS | [sass-lint](https://www.npmjs.com/package/sass-lint), [stylelint](https://github.com/stylelint/stylelint) |
 | SCSS | [prettier](https://github.com/prettier/prettier), [sass-lint](https://www.npmjs.com/package/sass-lint), [scss-lint](https://github.com/brigade/scss-lint), [stylelint](https://github.com/stylelint/stylelint) |
-| Scala | [scalac](http://scala-lang.org), [scalastyle](http://www.scalastyle.org) |
+| Scala | [fsc](https://www.scala-lang.org/old/sites/default/files/linuxsoft_archives/docu/files/tools/fsc.html), [scalac](http://scala-lang.org), [scalastyle](http://www.scalastyle.org) |
 | Slim | [slim-lint](https://github.com/sds/slim-lint) |
 | SML | [smlnj](http://www.smlnj.org/) |
 | Solidity | [solhint](https://github.com/protofire/solhint), [solium](https://github.com/duaraghav8/Solium) |
diff --git a/ale_linters/scala/fsc.vim b/ale_linters/scala/fsc.vim
new file mode 100644
index 00000000..17b26f0b
--- /dev/null
+++ b/ale_linters/scala/fsc.vim
@@ -0,0 +1,29 @@
+" Author: Nils Leuzinger - https://github.com/PawkyPenguin
+" Description: Basic scala support using fsc
+"
+function! ale_linters#scala#fsc#GetExecutable(buffer) abort
+    if index(split(getbufvar(a:buffer, '&filetype'), '\.'), 'sbt') >= 0
+        " Don't check sbt files
+        return ''
+    endif
+
+    return 'fsc'
+endfunction
+
+function! ale_linters#scala#fsc#GetCommand(buffer) abort
+    let l:executable = ale_linters#scala#fsc#GetExecutable(a:buffer)
+
+    if empty(l:executable)
+        return ''
+    endif
+
+    return ale#Escape(l:executable) . ' -Ystop-after:parser %t'
+endfunction
+
+call ale#linter#Define('scala', {
+\   'name': 'fsc',
+\   'executable_callback': 'ale_linters#scala#fsc#GetExecutable',
+\   'command_callback': 'ale_linters#scala#fsc#GetCommand',
+\   'callback': 'ale#handlers#scala#HandleScalacLintFormat',
+\   'output_stream': 'stderr',
+\})
diff --git a/ale_linters/scala/scalac.vim b/ale_linters/scala/scalac.vim
index 584aee74..551284af 100644
--- a/ale_linters/scala/scalac.vim
+++ b/ale_linters/scala/scalac.vim
@@ -4,7 +4,7 @@
 
 function! ale_linters#scala#scalac#GetExecutable(buffer) abort
     if index(split(getbufvar(a:buffer, '&filetype'), '\.'), 'sbt') >= 0
-        " Don't check sbt files with scalac.
+        " Don't check sbt files
         return ''
     endif
 
@@ -21,45 +21,10 @@ function! ale_linters#scala#scalac#GetCommand(buffer) abort
     return ale#Escape(l:executable) . ' -Ystop-after:parser %t'
 endfunction
 
-function! ale_linters#scala#scalac#Handle(buffer, lines) abort
-    " Matches patterns line the following:
-    "
-    " /var/folders/5q/20rgxx3x1s34g3m14n5bq0x80000gn/T/vv6pSsy/0:26: error: expected class or object definition
-    let l:pattern = '^.\+:\(\d\+\): \(\w\+\): \(.\+\)'
-    let l:output = []
-    let l:ln = 0
-
-    for l:line in a:lines
-        let l:ln = l:ln + 1
-        let l:match = matchlist(l:line, l:pattern)
-
-        if len(l:match) == 0
-            continue
-        endif
-
-        let l:text = l:match[3]
-        let l:type = l:match[2] is# 'error' ? 'E' : 'W'
-        let l:col = 0
-
-        if l:ln + 1 < len(a:lines)
-            let l:col = stridx(a:lines[l:ln + 1], '^')
-        endif
-
-        call add(l:output, {
-        \   'lnum': l:match[1] + 0,
-        \   'col': l:col + 1,
-        \   'text': l:text,
-        \   'type': l:type,
-        \})
-    endfor
-
-    return l:output
-endfunction
-
 call ale#linter#Define('scala', {
 \   'name': 'scalac',
 \   'executable_callback': 'ale_linters#scala#scalac#GetExecutable',
 \   'command_callback': 'ale_linters#scala#scalac#GetCommand',
-\   'callback': 'ale_linters#scala#scalac#Handle',
+\   'callback': 'ale#handlers#scala#HandleScalacLintFormat',
 \   'output_stream': 'stderr',
 \})
diff --git a/autoload/ale/handlers/scala.vim b/autoload/ale/handlers/scala.vim
new file mode 100644
index 00000000..3fe7a12e
--- /dev/null
+++ b/autoload/ale/handlers/scala.vim
@@ -0,0 +1,37 @@
+" Author: Nils Leuzinger - https://github.com/PawkyPenguin
+" Description: Scala linting handlers for scalac-like compilers.
+
+function! ale#handlers#scala#HandleScalacLintFormat(buffer, lines) abort
+    " Matches patterns line the following:
+    "
+    " /var/folders/5q/20rgxx3x1s34g3m14n5bq0x80000gn/T/vv6pSsy/0:26: error: expected class or object definition
+    let l:pattern = '^.\+:\(\d\+\): \(\w\+\): \(.\+\)'
+    let l:output = []
+    let l:ln = 0
+
+    for l:line in a:lines
+        let l:ln = l:ln + 1
+        let l:match = matchlist(l:line, l:pattern)
+
+        if len(l:match) == 0
+            continue
+        endif
+
+        let l:text = l:match[3]
+        let l:type = l:match[2] is# 'error' ? 'E' : 'W'
+        let l:col = 0
+
+        if l:ln + 1 < len(a:lines)
+            let l:col = stridx(a:lines[l:ln + 1], '^')
+        endif
+
+        call add(l:output, {
+        \   'lnum': l:match[1] + 0,
+        \   'col': l:col + 1,
+        \   'text': l:text,
+        \   'type': l:type,
+        \})
+    endfor
+
+    return l:output
+endfunction
diff --git a/doc/ale.txt b/doc/ale.txt
index 99d2befa..7ad46297 100644
--- a/doc/ale.txt
+++ b/doc/ale.txt
@@ -378,10 +378,10 @@ Notes:
 * Rust: `cargo`!!, `rls`, `rustc` (see |ale-integration-rust|), `rustfmt`
 * SASS: `sass-lint`, `stylelint`
 * SCSS: `prettier`, `sass-lint`, `scss-lint`, `stylelint`
-* Scala: `scalac`, `scalastyle`
+* Scala: `fsc`, `scalac`, `scalastyle`
 * Slim: `slim-lint`
 * SML: `smlnj`
-* Solidity: `solhint, solium`
+* Solidity: `solhint`, `solium`
 * Stylus: `stylelint`
 * SQL: `sqlint`
 * Swift: `swiftlint`, `swiftformat`
diff --git a/test/command_callback/test_fsc_command_callback.vader b/test/command_callback/test_fsc_command_callback.vader
new file mode 100644
index 00000000..451fa108
--- /dev/null
+++ b/test/command_callback/test_fsc_command_callback.vader
@@ -0,0 +1,17 @@
+Before:
+  runtime ale_linters/scala/fsc.vim
+
+After:
+  call ale#linter#Reset()
+
+Given scala(An empty Scala file):
+Execute(The default executable and command should be correct):
+  AssertEqual 'fsc', ale_linters#scala#fsc#GetExecutable(bufnr(''))
+  AssertEqual
+  \ ale#Escape('fsc') . ' -Ystop-after:parser %t',
+  \ ale_linters#scala#fsc#GetCommand(bufnr(''))
+
+Given scala.sbt(An empty SBT file):
+Execute(fsc should not be run for sbt files):
+  AssertEqual '', ale_linters#scala#fsc#GetExecutable(bufnr(''))
+  AssertEqual '', ale_linters#scala#fsc#GetCommand(bufnr(''))
diff --git a/test/handler/test_scalac_handler.vader b/test/command_callback/test_scalac_command_callback.vader
index fd222f67..6bb31b3f 100644
--- a/test/handler/test_scalac_handler.vader
+++ b/test/command_callback/test_scalac_command_callback.vader
@@ -5,7 +5,6 @@ After:
   call ale#linter#Reset()
 
 Given scala(An empty Scala file):
-
 Execute(The default executable and command should be correct):
   AssertEqual 'scalac', ale_linters#scala#scalac#GetExecutable(bufnr(''))
   AssertEqual
diff --git a/test/handler/test_scala_handler.vader b/test/handler/test_scala_handler.vader
new file mode 100644
index 00000000..3214bdbc
--- /dev/null
+++ b/test/handler/test_scala_handler.vader
@@ -0,0 +1,32 @@
+After:
+  call ale#linter#Reset()
+
+Execute(The handler should return an empty list with empty input):
+  AssertEqual [], ale#handlers#scala#HandleScalacLintFormat(bufnr(''), [])
+
+Execute(The handler should correctly parse error messages):
+  AssertEqual 
+  \ [
+  \   { 
+  \     'lnum': 4,
+  \     'col':  8,
+  \     'text': ''':'' expected but identifier found.',
+  \     'type': 'E'
+  \   },
+  \   {
+  \     'lnum': 6,
+  \     'col':  2,
+  \     'text': 'identifier expected but eof found.',
+  \     'type': 'E'
+  \   }
+  \ ],
+  \ ale#handlers#scala#HandleScalacLintFormat(bufnr(''),
+  \ [
+  \ "hi.scala:4: error: ':' expected but identifier found.",
+  \ "  Some stupid scala code",
+  \ "       ^",
+  \ "hi.scala:6: error: identifier expected but eof found.",
+  \ ")",
+  \ " ^",
+  \ "two errors found",
+  \ ])