feat: add flake8 for python lint

README.md

@@ -36,6 +36,7 @@
 
 - [x] [clang-tidy](https://clang.llvm.org/extra/clang-tidy/)
 - [ ] [codespell](https://github.com/codespell-project/codespell)
+- [x] [flake8](https://github.com/PyCQA/flake8)
 - [x] [hadolint](https://github.com/hadolint/hadolint)
 - [x] [luacheck](https://github.com/lunarmodules/luacheck)
 - [x] [pylint](https://github.com/PyCQA/pylint)

lua/guard-collection/linter/flake8.lua

@@ -0,0 +1,18 @@
+local lint = require('guard.lint')
+
+return {
+  cmd = 'flake8',
+  args = { '--format', 'default', '-', '--stdin-display-name' },
+  stdin = true,
+  fname = true,
+  parse = lint.from_regex({
+    source = 'flake8',
+    regex = ':(%d+):(%d+):%s(%a)(%w+) (.+)',
+    severities = {
+      E = lint.severities.error,
+      W = lint.severities.warning,
+      C = lint.severities.warning,
+      F = lint.severities.info,
+    },
+  }),
+}

test/linter/flake8_spec.lua

@@ -0,0 +1,106 @@
+describe('flake8', function()
+  it('can lint', function()
+    local ft = require('guard.filetype')
+    ft('python'):lint('flake8')
+    require('guard').setup()
+
+    local diagnostics = require('test.linter.helper').test_with('python', {
+      [[import os]],
+      [[]],
+      [[def foo(n):]],
+      [[    if n == 0:]],
+      [[         return  bar]],
+      [[print("it's too long sentence to be displayed in one line, blah blah blah blah")]],
+    })
+    assert.are.same({
+      {
+        bufnr = 3,
+        col = 0,
+        end_col = 0,
+        end_lnum = 0,
+        lnum = 0,
+        message = "'os' imported but unused [401]",
+        namespace = 4,
+        severity = 3,
+        source = 'flake8',
+      },
+      {
+        bufnr = 3,
+        col = 0,
+        end_col = 0,
+        end_lnum = 2,
+        lnum = 2,
+        message = 'expected 2 blank lines, found 1 [302]',
+        namespace = 4,
+        severity = 1,
+        source = 'flake8',
+      },
+      {
+        bufnr = 3,
+        col = 9,
+        end_col = 9,
+        end_lnum = 4,
+        lnum = 4,
+        message = 'indentation is not a multiple of 4 [111]',
+        namespace = 4,
+        severity = 1,
+        source = 'flake8',
+      },
+      {
+        bufnr = 3,
+        col = 9,
+        end_col = 9,
+        end_lnum = 4,
+        lnum = 4,
+        message = 'over-indented [117]',
+        namespace = 4,
+        severity = 1,
+        source = 'flake8',
+      },
+      {
+        bufnr = 3,
+        col = 15,
+        end_col = 15,
+        end_lnum = 4,
+        lnum = 4,
+        message = 'multiple spaces after keyword [271]',
+        namespace = 4,
+        severity = 1,
+        source = 'flake8',
+      },
+      {
+        bufnr = 3,
+        col = 17,
+        end_col = 17,
+        end_lnum = 4,
+        lnum = 4,
+        message = "undefined name 'bar' [821]",
+        namespace = 4,
+        severity = 3,
+        source = 'flake8',
+      },
+      {
+        bufnr = 3,
+        col = 0,
+        end_col = 0,
+        end_lnum = 5,
+        lnum = 5,
+        message = 'expected 2 blank lines after class or function definition, found 0 [305]',
+        namespace = 4,
+        severity = 1,
+        source = 'flake8',
+      },
+      {
+        bufnr = 3,
+        col = 79,
+        end_col = 79,
+        end_lnum = 5,
+        lnum = 5,
+        message = 'line too long (80 > 79 characters) [501]',
+        namespace = 4,
+        severity = 1,
+        source = 'flake8',
+      },
+    }, diagnostics)
+  end)
+end)

test/setup.sh

@@ -8,7 +8,7 @@ sudo apt-get install -qqq \
     clang-format clang-tidy fish elixir &
 luarocks install luacheck &
 go install github.com/segmentio/golines@latest &
-pip -qqq install autopep8 black djhtml isort pylint yapf &
+pip -qqq install autopep8 black djhtml flake8 isort pylint yapf &
 npm install -g --silent \
     prettier @fsouza/prettierd sql-formatter shellcheck shfmt &
 gem install -q rubocop &