Execute(The Rust handler should handle rustc output):
  call ale#test#SetFilename('src/playpen.rs')

  AssertEqual
  \ [
  \   {
  \     'lnum': 15,
  \     'end_lnum': 15,
  \     'type': 'E',
  \     'col': 418,
  \     'end_col': 421,
  \     'text': 'expected one of `.`, `;`, `?`, `}`, or an operator, found `for`',
  \   },
  \   {
  \      'lnum': 13,
  \      'end_lnum': 13,
  \      'type': 'E',
  \      'col': 407,
  \      'end_col': 410,
  \      'text': 'no method named `wat` found for type `std::string::String` in the current scope',
  \   },
  \ ],
  \ ale#handlers#rust#HandleRustErrors(bufnr(''), [
  \   '',
  \   'ignore this',
  \   json_encode({
  \     'message': 'expected one of `.`, `;`, `?`, `}`, or an operator, found `for`',
  \     'code': v: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': v:true,
  \         'label': v:null,
  \       },
  \     ],
  \   }),
  \   json_encode({
  \     'message': 'main function not found',
  \     'code': v:null,
  \     'level': 'error',
  \     'spans': [],
  \   }),
  \   json_encode({
  \     'code': v:null,
  \     'level': 'error',
  \     'message': 'no method named `wat` found for type `std::string::String` in the current scope',
  \     'spans': [
  \       {
  \         'byte_end': 410,
  \         'byte_start': 407,
  \         'column_end': 10,
  \         'column_start': 7,
  \         'file_name': '<anon>',
  \         'is_primary': v:true,
  \         'label': v:null,
  \         'line_end': 13,
  \         'line_start': 13,
  \       }
  \     ]
  \   }),
  \   json_encode({
  \     'code': v:null,
  \     'level': 'error',
  \     'message': 'aborting due to previous error',
  \     'spans': [
  \     ]
  \   }),
  \ ])

Execute(The Rust handler should handle cargo output):
  call ale#test#SetFilename('src/playpen.rs')

  AssertEqual
  \ [
  \   {
  \     'lnum': 15,
  \     'end_lnum': 15,
  \     'type': 'E',
  \     'col': 11505,
  \     'end_col': 11508,
  \     'text': 'expected one of `.`, `;`, `?`, `}`, or an operator, found `for`',
  \   },
  \   {
  \     'lnum': 13,
  \     'end_lnum': 13,
  \     'type': 'E',
  \     'col': 11494,
  \     'end_col': 11497,
  \     'text': 'no method named `wat` found for type `std::string::String` in the current scope',
  \   },
  \ ],
  \ ale#handlers#rust#HandleRustErrors(bufnr(''), [
  \   '',
  \   'ignore this',
  \   json_encode({
  \     'message': {
  \       'code': v:null,
  \       'level': 'error',
  \       'message': 'expected one of `.`, `;`, `?`, `}`, or an operator, found `for`',
  \       'spans': [
  \         {
  \           'byte_end': 11508,
  \           'byte_start': 11505,
  \           'column_end': 8,
  \           'column_start': 5,
  \           'file_name': ale#path#Simplify('src/playpen.rs'),
  \           'is_primary': v:true,
  \           'label': v:null,
  \           'line_end': 15,
  \           'line_start': 15,
  \         }
  \       ]
  \     },
  \   }),
  \   json_encode({
  \     'message': {
  \       'code': v:null,
  \       'level': 'error',
  \       'message': 'no method named `wat` found for type `std::string::String` in the current scope',
  \       'spans': [
  \         {
  \           'byte_end': 11497,
  \           'byte_start': 11494,
  \           'column_end': 10,
  \           'column_start': 7,
  \           'file_name': ale#path#Simplify('src/playpen.rs'),
  \           'is_primary': v:true,
  \           'label': v:null,
  \           'line_end': 13,
  \           'line_start': 13,
  \         }
  \       ]
  \     },
  \   }),
  \   json_encode({
  \     'message': {
  \       'code': v:null,
  \       'level': 'error',
  \       'message': 'aborting due to previous error',
  \       'spans': [
  \       ]
  \     },
  \   }),
  \ ])

Execute(The Rust handler should should errors from expansion spans):
  AssertEqual
  \ [
  \   {
  \     'lnum': 4,
  \     'end_lnum': 4,
  \     'type': 'E',
  \     'col': 52,
  \     'end_col': 54,
  \     'text': 'mismatched types: expected bool, found integral variable',
  \   },
  \ ],
  \ ale#handlers#rust#HandleRustErrors(bufnr(''), [
  \   json_encode({
  \     'message': {
  \       'code': v:null,
  \       'level': 'error',
  \       'message': 'mismatched types',
  \       'spans': [
  \         {
  \           'byte_end': 1,
  \           'byte_start': 1,
  \           'column_end': 1,
  \           'column_start': 1,
  \           'file_name': ale#path#Simplify('src/other.rs'),
  \           'is_primary': v:true,
  \           'label': 'some other error',
  \           'line_end': 4,
  \           'line_start': 4,
  \           'expansion': {
  \             'span': {
  \               'byte_end': 54,
  \               'byte_start': 52,
  \               'column_end': 23,
  \               'column_start': 21,
  \               'file_name': ale#path#Simplify('src/playpen.rs'),
  \               'is_primary': v:true,
  \               'label': 'expected bool, found integral variable',
  \               'line_end': 4,
  \               'line_start': 4,
  \             }
  \           }
  \         }
  \       ]
  \     },
  \   }),
  \ ])

Execute(The Rust handler should show detailed errors):
  call ale#test#SetFilename('src/playpen.rs')

  AssertEqual
  \ [
  \   {
  \     'lnum': 4,
  \     'end_lnum': 4,
  \     'type': 'E',
  \     'col': 52,
  \     'end_col': 54,
  \     'text': 'mismatched types: expected bool, found integral variable',
  \   },
  \ ],
  \ ale#handlers#rust#HandleRustErrors(bufnr(''), [
  \   '',
  \   'ignore this',
  \   json_encode({
  \     'message': {
  \       'code': v:null,
  \       'level': 'error',
  \       'message': 'mismatched types',
  \       'spans': [
  \         {
  \           'byte_end': 54,
  \           'byte_start': 52,
  \           'column_end': 23,
  \           'column_start': 21,
  \           'expansion': v:null,
  \           'file_name': ale#path#Simplify('src/playpen.rs'),
  \           'is_primary': v:true,
  \           'label': 'expected bool, found integral variable',
  \           'line_end': 4,
  \           'line_start': 4,
  \         }
  \       ]
  \     },
  \   }),
  \   json_encode({
  \     'message': {
  \       'code': v:null,
  \       'level': 'error',
  \       'message': 'aborting due to previous error(s)',
  \       'spans': [
  \       ]
  \     },
  \   }),
  \ ])

Execute(The Rust handler should find correct files):
  call ale#test#SetFilename('src/noerrors/mod.rs')

  AssertEqual
  \ [],
  \ ale#handlers#rust#HandleRustErrors(bufnr(''), [
  \   '',
  \   'ignore this',
  \   json_encode({
  \     'message': {
  \       'code': v:null,
  \       'level': 'error',
  \       'message': 'unresolved import `Undefined`',
  \       'spans': [
  \         {
  \           'byte_end': 103,
  \           'byte_start': 94,
  \           'column_end': 14,
  \           'column_start': 5,
  \           'file_name': 'src/haserrors/mod.rs',
  \           'is_primary': v:true,
  \           'label': 'no `Undefined` in the root',
  \           'line_end': 1,
  \           'line_start': 1,
  \         }
  \       ]
  \     },
  \   }),
  \   json_encode({
  \     'message': {
  \       'code': v:null,
  \       'level': 'error',
  \       'message': 'aborting due to previous error',
  \       'spans': [
  \       ]
  \     },
  \   }),
  \ ])