Add TAP reporter

To provide better compatibility with more tools, I thought that it would
be nice to add a TAP reporter to SCSS-Lint.

  http://testanything.org/

For a list of TAP consumers, look at

  http://testanything.org/consumers.html

Fixes #698

README.md

@@ -292,6 +292,44 @@ Outputs JSON with filenames and an array of issue objects.
 }
 ```
 
+### TAP
+
+Outputs [TAP version 13](https://testanything.org) format.
+
+```
+TAP version 13
+1..5
+ok 1 - ok1.scss
+not ok 2 - not-ok1.scss:123:10 SCSSLint::Linter::PrivateNamingConvention
+  ---
+  message: Description of lint 1
+  severity: warning
+  data:
+    file: not-ok1.scss
+    line: 123
+    column: 10
+  ---
+not ok 3 - not-ok2.scss:20:2 SCSSLint::Linter::PrivateNamingConvention
+  ---
+  message: Description of lint 2
+  severity: error
+  data:
+    file: not-ok2.scss
+    line: 20
+    column: 2
+  ---
+not ok 4 - not-ok2.scss:21:3 SCSSLint::Linter::PrivateNamingConvention
+  ---
+  message: Description of lint 3
+  severity: warning
+  data:
+    file: not-ok2.scss
+    line: 21
+    column: 3
+  ---
+ok 5 - ok2.scss
+```
+
 ### Plugins
 
 There are also formatters that integrate with third-party tools which are available as plugins.

lib/scss_lint/reporter/tap_reporter.rb

@@ -0,0 +1,123 @@
+module SCSSLint
+  # Reports in TAP format.
+  # http://testanything.org/
+  class Reporter::TAPReporter < Reporter
+    TAP_VERSION = 'TAP version 13'.freeze
+
+    def report_lints
+      output = [TAP_VERSION, format_plan(files, lints)]
+      return format_output(output) unless files.any?
+
+      output.concat(format_files(files, lints))
+      format_output(output)
+    end
+
+  private
+
+    # @param files [Array<String>]
+    # @param lints [Array<SCSSLint::Lint>]
+    # @return [String]
+    def format_plan(files, lints)
+      files_with_lints = lints.map(&:filename).uniq
+      extra_lines = lints.count - files_with_lints.count
+      comment = files.count == 0 ? ' # No files to lint' : ''
+      "1..#{files.count + extra_lines}#{comment}"
+    end
+
+    # @param files [Array<String>]
+    # @param lints [Array<SCSSLint::Lint>]
+    # @return [Array<String>] one item per ok file or not ok lint
+    def format_files(files, lints)
+      unless lints.any?
+        # There are no lints, so we can take a shortcut and just output an ok
+        # test line for every file.
+        return files.map.with_index do |filename, index|
+          format_ok(filename, index + 1)
+        end
+      end
+
+      # There are lints, so we need to go through each file, find the lints
+      # for the file, and add them to the output.
+
+      # Since we'll be looking up lints by filename for each filename, we want
+      # to make a first pass to group all of the lints by filename to make
+      # lookup fast.
+      grouped_lints = group_lints_by_filename(lints)
+
+      test_number = 1
+      files.map do |filename|
+        if grouped_lints.key?(filename)
+          # This file has lints, so we want to generate a "not ok" test line for
+          # each failing lint.
+          grouped_lints[filename].map do |lint|
+            formatted = format_not_ok(lint, test_number)
+            test_number += 1
+            formatted
+          end
+        else
+          formatted = format_ok(filename, test_number)
+          test_number += 1
+          [formatted]
+        end
+      end.flatten
+    end
+
+    # @param lints [Array<SCSSLint::Lint>]
+    # @return [Hash] keyed by filename, values are arrays of lints
+    def group_lints_by_filename(lints)
+      grouped_lints = {}
+      lints.each do |lint|
+        grouped_lints[lint.filename] ||= []
+        grouped_lints[lint.filename] << lint
+      end
+      grouped_lints
+    end
+
+    # @param filename [String]
+    # @param test_number [Number]
+    # @return [String]
+    def format_ok(filename, test_number)
+      "ok #{test_number} - #{filename}"
+    end
+
+    # @param lint [SCSSLint::Lint]
+    # @param test_number [Number]
+    # @return [String]
+    def format_not_ok(lint, test_number)
+      location = lint.location
+      test_line_description = "#{lint.filename}:#{location.line}:#{location.column}"
+      test_line_description += " #{lint.linter.name}" if lint.linter
+
+      <<-EOS.strip
+not ok #{test_number} - #{test_line_description}
+  ---
+  message: #{lint.description}
+  severity: #{lint.severity}
+  data:
+    file: #{lint.filename}
+    line: #{lint.location.line}
+    column: #{lint.location.column}
+  ---
+      EOS
+    end
+
+    # @param output [Array<String>]
+    # @return [String]
+    def format_output(output)
+      output.join("\n") + "\n"
+    end
+
+    def location(lint)
+      "#{log.cyan(lint.filename)}:#{log.magenta(lint.location.line.to_s)}"
+    end
+
+    def type(lint)
+      lint.error? ? log.red('[E]') : log.yellow('[W]')
+    end
+
+    def message(lint)
+      linter_name = log.green("#{lint.linter.name}: ") if lint.linter
+      "#{linter_name}#{lint.description}"
+    end
+  end
+end

spec/scss_lint/reporter/tap_reporter_spec.rb

@@ -0,0 +1,97 @@
+require 'spec_helper'
+
+describe SCSSLint::Reporter::TAPReporter do
+  let(:logger) { SCSSLint::Logger.new($stdout) }
+  subject { described_class.new(lints, filenames, logger) }
+
+  describe '#report_lints' do
+    context 'when there are no files' do
+      let(:filenames) { [] }
+      let(:lints) { [] }
+
+      it 'returns the TAP version, plan, and explanation' do
+        subject.report_lints.should == "TAP version 13\n1..0 # No files to lint\n"
+      end
+    end
+
+    context 'when there are files but no lints' do
+      let(:filenames) { ['file.scss', 'another-file.scss'] }
+      let(:lints) { [] }
+
+      it 'returns the TAP version, plan, and ok test lines' do
+        subject.report_lints.should eq(<<-EOS)
+TAP version 13
+1..2
+ok 1 - file.scss
+ok 2 - another-file.scss
+        EOS
+      end
+    end
+
+    context 'when there are some lints' do
+      let(:filenames) { %w[ok1.scss not-ok1.scss not-ok2.scss ok2.scss] }
+
+      let(:lints) do
+        [
+          SCSSLint::Lint.new(
+            SCSSLint::Linter::PrivateNamingConvention,
+            filenames[1],
+            SCSSLint::Location.new(123, 10, 8),
+            'Description of lint 1',
+            :warning
+          ),
+          SCSSLint::Lint.new(
+            SCSSLint::Linter::PrivateNamingConvention,
+            filenames[2],
+            SCSSLint::Location.new(20, 2, 6),
+            'Description of lint 2',
+            :error
+          ),
+          SCSSLint::Lint.new(
+            SCSSLint::Linter::PrivateNamingConvention,
+            filenames[2],
+            SCSSLint::Location.new(21, 3, 4),
+            'Description of lint 3',
+            :warning
+          ),
+        ]
+      end
+
+      it 'returns the TAP version, plan, and correct test lines' do
+        subject.report_lints.should eq(<<-EOS)
+TAP version 13
+1..5
+ok 1 - ok1.scss
+not ok 2 - not-ok1.scss:123:10 SCSSLint::Linter::PrivateNamingConvention
+  ---
+  message: Description of lint 1
+  severity: warning
+  data:
+    file: not-ok1.scss
+    line: 123
+    column: 10
+  ---
+not ok 3 - not-ok2.scss:20:2 SCSSLint::Linter::PrivateNamingConvention
+  ---
+  message: Description of lint 2
+  severity: error
+  data:
+    file: not-ok2.scss
+    line: 20
+    column: 2
+  ---
+not ok 4 - not-ok2.scss:21:3 SCSSLint::Linter::PrivateNamingConvention
+  ---
+  message: Description of lint 3
+  severity: warning
+  data:
+    file: not-ok2.scss
+    line: 21
+    column: 3
+  ---
+ok 5 - ok2.scss
+        EOS
+      end
+    end
+  end
+end