Add ShellCheck linter (#155)

Aptfile

@@ -0,0 +1 @@
+shellcheck

README.md

@@ -22,6 +22,7 @@ This service uses the following linters:
   * [rubocop](https://github.com/bbatsov/rubocop) for Ruby
   * [sass-lint](https://github.com/sasstools/sass-lint) for SASS
   * [scss-lint](https://github.com/brigade/scss-lint) for SCSS
+  * [shellcheck](https://github.com/koalaman/shellcheck) for shell scripts
   * [slim-lint](https://github.com/sds/slim-lint) for Slim
   * [stylelint](https://github.com/stylelint/stylelint) for SCSS/CSS
   * [tslint](https://github.com/palantir/tslint) for TypeScript

bin/setup

@@ -22,6 +22,15 @@ mix compile
 # Python setup
 python -m pip install flake8
 
+# ShellCheck setup
+if [ "$(uname)" = "Darwin" ]; then
+  brew install shellcheck
+else
+  sudo apt-add-repository "deb http://archive.ubuntu.com/ubuntu trusty-backports main restricted universe"
+  sudo apt-get update
+  sudo apt-get install shellcheck
+fi
+
 # Add binstubs to PATH via export PATH=".git/safe/../../bin:$PATH" in ~/.zshenv
 mkdir -p .git/safe
 

jobs/linters_job.rb

@@ -13,6 +13,7 @@
 require "linters/rubocop/options"
 require "linters/sass_lint/options"
 require "linters/scss_lint/options"
+require "linters/shellcheck/options"
 require "linters/slim_lint/options"
 require "linters/stylelint/options"
 require "linters/tslint/options"

lib/linters/shellcheck/options.rb

@@ -0,0 +1,33 @@
+require "linters/base/options"
+require "linters/shellcheck/tokenizer"
+
+module Linters
+  module Shellcheck
+    class Options < Linters::Base::Options
+      def command
+        "shellcheck #{command_options} #{filepath}"
+      end
+
+      def tokenizer
+        Tokenizer.new
+      end
+
+      def config_content; end
+
+      private
+
+      attr_reader :filepath, :raw_config_content
+
+      def command_options
+        excluded_rules = parsed_config["exclude"]
+        if excluded_rules
+          "-e #{excluded_rules.join(',')}"
+        end
+      end
+
+      def parsed_config
+        YAML.safe_load(config).to_h
+      end
+    end
+  end
+end

lib/linters/shellcheck/tokenizer.rb

@@ -0,0 +1,31 @@
+module Linters
+  module Shellcheck
+    class Tokenizer
+      VIOLATION_REGEX = /\A
+        \s*In\s
+        (?<file>.+)\sline\s
+        (?<line_number>\d+).*\^--\s
+        (?<code>\w+):\s
+        (?<message>.*)
+      \z/xm
+
+      def parse(text)
+        text.split("\n\n").map { |line| tokenize(line) }.compact
+      end
+
+      private
+
+      def tokenize(line)
+        matches = VIOLATION_REGEX.match(line)
+
+        if matches
+          line_number = matches[:line_number].to_i
+          {
+            line: line_number,
+            message: matches[:message].strip,
+          }
+        end
+      end
+    end
+  end
+end

spec/integrations/shellcheck_spec.rb

@@ -0,0 +1,58 @@
+require "jobs/linters_job"
+
+RSpec.describe LintersJob, "for ShellCheck" do
+  include LintersHelper
+
+  context "when file contains violations" do
+    it "reports violations" do
+      expect_violations_in_file(
+        config: "",
+        content: content,
+        filename: "foo/bar.sh",
+        linter_name: "shellcheck",
+        violations: [
+          {
+            line: 3,
+            message: "Double quote to prevent globbing and word splitting.",
+          },
+          {
+            line: 4,
+            message: "foo appears unused. Verify it or export it.",
+          },
+        ],
+      )
+    end
+  end
+
+  context "when custom configuraton is provided" do
+    it "respects the custom configuration" do
+      config = <<~CONFIG
+        exclude:
+          - SC2086 # Double quote to prevent globbing and word splitting.
+      CONFIG
+
+      expect_violations_in_file(
+        config: config,
+        content: content,
+        filename: "foo/bar.sh",
+        linter_name: "shellcheck",
+        violations: [
+          {
+            line: 4,
+            message: "foo appears unused. Verify it or export it.",
+          },
+        ],
+      )
+    end
+  end
+
+  def content
+    <<~SCRIPT
+      #!/bin/sh
+      hello_world () {
+        echo $1
+        foo=42
+      }
+    SCRIPT
+  end
+end