Cover the Rust handler with some tests

ale_linters/rust/cargo.vim

@@ -1,7 +1,6 @@
 " Author: Daniel Schemala <istjanichtzufassen@gmail.com>
 " Description: rustc invoked by cargo for rust files
 
-
 function! ale_linters#rust#cargo#GetCargoExecutable(bufnr) abort
     if ale#util#FindNearestFile(a:bufnr, 'Cargo.toml') !=# ''
         return 'cargo'
@@ -16,6 +15,6 @@ call ale#linter#Define('rust', {
 \   'name': 'cargo',
 \   'executable_callback': 'ale_linters#rust#cargo#GetCargoExecutable',
 \   'command': 'cargo build --message-format=json -q',
-\   'callback': 'ale_linters#rust#rustc#HandleRustcErrors',
+\   'callback': 'ale#handlers#rust#HandleRustErrors',
 \   'output_stream': 'stdout',
 \})

ale_linters/rust/rustc.vim

@@ -1,86 +1,6 @@
 " Author: Daniel Schemala <istjanichtzufassen@gmail.com>
 " Description: rustc for rust files
 
-if !exists('g:ale_rust_ignore_error_codes')
-    let g:ale_rust_ignore_error_codes = []
-endif
-
-
-function! ale_linters#rust#rustc#HandleRustcErrors(buffer_number, errorlines) abort
-    let l:file_name = fnamemodify(bufname(a:buffer_number), ':t')
-    let l:output = []
-
-    for l:errorline in a:errorlines
-        " ignore everything that is not Json
-        if l:errorline !~# '^{'
-            continue
-        endif
-
-        let l:error = json_decode(l:errorline)
-
-        if has_key(l:error, 'message') && type(l:error.message) == type({})
-            let l:error = l:error.message
-        endif
-
-        if !has_key(l:error, 'code')
-            continue
-        endif
-
-        if !empty(l:error.code) && index(g:ale_rust_ignore_error_codes, l:error.code.code) > -1
-            continue
-        endif
-
-        for l:span in l:error.spans
-            let l:span.file_name = fnamemodify(l:span.file_name, ':t')
-            if l:span.is_primary &&
-                \   (l:span.file_name ==# l:file_name || l:span.file_name ==# '<anon>')
-                call add(l:output, {
-                \   'bufnr': a:buffer_number,
-                \   'lnum': l:span.line_start,
-                \   'vcol': 0,
-                \   'col': l:span.byte_start,
-                \   'nr': -1,
-                \   'text': l:error.message,
-                \   'type': toupper(l:error.level[0]),
-                \})
-            else
-                " when the error is caused in the expansion of a macro, we have
-                " to bury deeper
-                let l:root_cause = s:FindErrorInExpansion(l:span, l:file_name)
-
-                if !empty(l:root_cause)
-                    call add(l:output, {
-                    \   'bufnr': a:buffer_number,
-                    \   'lnum': l:root_cause[0],
-                    \   'vcol': 0,
-                    \   'col': l:root_cause[1],
-                    \   'nr': -1,
-                    \   'text': l:error.message,
-                    \   'type': toupper(l:error.level[0]),
-                    \})
-                endif
-            endif
-        endfor
-    endfor
-
-    return l:output
-endfunction
-
-
-" returns: a list [lnum, col] with the location of the error or []
-function! s:FindErrorInExpansion(span, file_name) abort
-    if a:span.file_name ==# a:file_name
-        return [a:span.line_start, a:span.byte_start]
-    endif
-
-    if !empty(a:span.expansion)
-        return s:FindErrorInExpansion(a:span.expansion.span, a:file_name)
-    endif
-
-    return []
-endfunction
-
-
 function! ale_linters#rust#rustc#RustcCommand(buffer_number) abort
     " Try to guess the library search path. If the project is managed by cargo,
     " it's usually <project root>/target/debug/deps/ or
@@ -98,11 +18,10 @@ function! ale_linters#rust#rustc#RustcCommand(buffer_number) abort
     return 'rustc --error-format=json -Z no-trans ' . l:dependencies . ' -'
 endfunction
 
-
 call ale#linter#Define('rust', {
 \   'name': 'rustc',
 \   'executable': 'rustc',
 \   'command_callback': 'ale_linters#rust#rustc#RustcCommand',
-\   'callback': 'ale_linters#rust#rustc#HandleRustcErrors',
+\   'callback': 'ale#handlers#rust#HandleRustErrors',
 \   'output_stream': 'stderr',
 \})

autoload/ale/handlers/rust.vim

@@ -0,0 +1,90 @@
+" Author: Daniel Schemala <istjanichtzufassen@gmail.com>,
+"   w0rp <devw0rp@gmail.com>
+"
+" Description: This file implements handlers specific to Rust.
+
+if !exists('g:ale_rust_ignore_error_codes')
+    let g:ale_rust_ignore_error_codes = []
+endif
+
+" returns: a list [lnum, col] with the location of the error or []
+function! s:FindErrorInExpansion(span, file_name) abort
+    if a:span.file_name ==# a:file_name
+        return [a:span.line_start, a:span.byte_start]
+    endif
+
+    if !empty(a:span.expansion)
+        return s:FindErrorInExpansion(a:span.expansion.span, a:file_name)
+    endif
+
+    return []
+endfunction
+
+" A handler function which accepts a file name, to make unit testing easier.
+function! ale#handlers#rust#HandleRustErrorsForFile(buffer, full_filename, lines) abort
+    let l:filename = fnamemodify(a:full_filename, ':t')
+    let l:output = []
+
+    for l:errorline in a:lines
+        " ignore everything that is not Json
+        if l:errorline !~# '^{'
+            continue
+        endif
+
+        let l:error = json_decode(l:errorline)
+
+        if has_key(l:error, 'message') && type(l:error.message) == type({})
+            let l:error = l:error.message
+        endif
+
+        if !has_key(l:error, 'code')
+            continue
+        endif
+
+        if !empty(l:error.code) && index(g:ale_rust_ignore_error_codes, l:error.code.code) > -1
+            continue
+        endif
+
+        for l:span in l:error.spans
+            let l:span_filename = fnamemodify(l:span.file_name, ':t')
+
+            if (
+            \   l:span.is_primary
+            \   && (l:span_filename ==# l:filename || l:span_filename ==# '<anon>')
+            \)
+                call add(l:output, {
+                \   'bufnr': a:buffer,
+                \   'lnum': l:span.line_start,
+                \   'vcol': 0,
+                \   'col': l:span.byte_start,
+                \   'nr': -1,
+                \   'text': l:error.message,
+                \   'type': toupper(l:error.level[0]),
+                \})
+            else
+                " when the error is caused in the expansion of a macro, we have
+                " to bury deeper
+                let l:root_cause = s:FindErrorInExpansion(l:span, l:filename)
+
+                if !empty(l:root_cause)
+                    call add(l:output, {
+                    \   'bufnr': a:buffer,
+                    \   'lnum': l:root_cause[0],
+                    \   'vcol': 0,
+                    \   'col': l:root_cause[1],
+                    \   'nr': -1,
+                    \   'text': l:error.message,
+                    \   'type': toupper(l:error.level[0]),
+                    \})
+                endif
+            endif
+        endfor
+    endfor
+
+    return l:output
+endfunction
+
+" A handler for output for Rust linters.
+function! ale#handlers#rust#HandleRustErrors(buffer, lines) abort
+    return ale#handlers#rust#HandleRustErrorsForFile(a:buffer, bufname(a:buffer), a:lines)
+endfunction

test/test_rust_handler.vader

@@ -0,0 +1,28 @@
+Execute(The Rust handler should handle rustc output):
+  AssertEqual
+  \ [
+  \   {'lnum': 15, 'bufnr': 347, 'vcol': 0, 'nr': -1, 'type': 'E', 'col': 418, 'text': 'expected one of `.`, `;`, `?`, `}`, or an operator, found `for`'},
+  \   {'lnum': 13, 'bufnr': 347, 'vcol': 0, 'nr': -1, 'type': 'E', 'col': 407, 'text': 'no method named `wat` found for type `std::string::String` in the current scope'},
+  \ ],
+  \ ale#handlers#rust#HandleRustErrorsForFile(347, 'src/playpen.rs', [
+  \   '',
+  \   'ignore this',
+  \   '{"message":"expected one of `.`, `;`, `?`, `}`, or an operator, found `for`","code":null,"level":"error","spans":[{"file_name":"<anon>","byte_start":418,"byte_end":421,"line_start":15,"line_end":15,"column_start":5,"column_end":8,"is_primary":true,"text":[{"text":"    for chr in source.trim().chars() {","highlight_start":5,"highlight_end":8}],"label":null,"suggested_replacement":null,"expansion":null}],"children":[],"rendered":null}',
+  \   '{"message":"main function not found","code":null,"level":"error","spans":[],"children":[],"rendered":null}',
+  \   '{"message":"no method named `wat` found for type `std::string::String` in the current scope","code":null,"level":"error","spans":[{"file_name":"<anon>","byte_start":407,"byte_end":410,"line_start":13,"line_end":13,"column_start":7,"column_end":10,"is_primary":true,"text":[{"text":"    s.wat()","highlight_start":7,"highlight_end":10}],"label":null,"suggested_replacement":null,"expansion":null}],"children":[],"rendered":null}',
+  \   '{"message":"aborting due to previous error","code":null,"level":"error","spans":[],"children":[],"rendered":null}',
+  \ ])
+
+Execute(The Rust handler should handle cargo output):
+  AssertEqual
+  \ [
+  \   {'lnum': 15, 'bufnr': 347, 'vcol': 0, 'nr': -1, 'type': 'E', 'col': 11505, 'text': 'expected one of `.`, `;`, `?`, `}`, or an operator, found `for`'},
+  \   {'lnum': 13, 'bufnr': 347, 'vcol': 0, 'nr': -1, 'type': 'E', 'col': 11494, 'text': 'no method named `wat` found for type `std::string::String` in the current scope'},
+  \ ],
+  \ ale#handlers#rust#HandleRustErrorsForFile(347, 'src/playpen.rs', [
+  \   '',
+  \   'ignore this',
+  \   '{"message":{"children":[],"code":null,"level":"error","message":"expected one of `.`, `;`, `?`, `}`, or an operator, found `for`","rendered":null,"spans":[{"byte_end":11508,"byte_start":11505,"column_end":8,"column_start":5,"expansion":null,"file_name":"src/playpen.rs","is_primary":true,"label":null,"line_end":15,"line_start":15,"suggested_replacement":null,"text":[{"highlight_end":8,"highlight_start":5,"text":"    for chr in source.trim().chars() {"}]}]},"package_id":"update 0.0.1 (path+file:///home/w0rp/Downloads/rust-by-example)","reason":"compiler-message","target":{"kind":["bin"],"name":"update","src_path":"/home/w0rp/Downloads/rust-by-example/src/main.rs"}}',
+  \   '{"message":{"children":[],"code":null,"level":"error","message":"no method named `wat` found for type `std::string::String` in the current scope","rendered":null,"spans":[{"byte_end":11497,"byte_start":11494,"column_end":10,"column_start":7,"expansion":null,"file_name":"src/playpen.rs","is_primary":true,"label":null,"line_end":13,"line_start":13,"suggested_replacement":null,"text":[{"highlight_end":10,"highlight_start":7,"text":"    s.wat()"}]}]},"package_id":"update 0.0.1 (path+file:///home/w0rp/Downloads/rust-by-example)","reason":"compiler-message","target":{"kind":["bin"],"name":"update","src_path":"/home/w0rp/Downloads/rust-by-example/src/main.rs"}}',
+  \   '{"message":{"children":[],"code":null,"level":"error","message":"aborting due to previous error","rendered":null,"spans":[]},"package_id":"update 0.0.1 (path+file:///home/w0rp/Downloads/rust-by-example)","reason":"compiler-message","target":{"kind":["bin"],"name":"update","src_path":"/home/w0rp/Downloads/rust-by-example/src/main.rs"}}',
+  \ ])