From 225c01e2a2a32c9da7683d06ef069439e7b32aed Mon Sep 17 00:00:00 2001
From: Koichi ITO <koic.ito@gmail.com>
Date: Thu, 10 Sep 2020 18:53:25 +0900
Subject: [PATCH] [Fix #8673] Fix the JSON parse error when specifying
 `--format=json` and `--stdin`

Fixes #8673.

This PR returns only JSON result when specifying `--format=json` and `--stdin`
to fix the JSON parse error. Similar HTML and JUnit formatters are targeted as well.
---
 CHANGELOG.md                              |  1 +
 lib/rubocop/cli/command/execute_runner.rb |  8 ++++++
 spec/rubocop/cli/cli_options_spec.rb      | 30 +++++++++++++++++++++++
 3 files changed, 39 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 160acd93bf9..49dc1dff9e1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -35,6 +35,7 @@
 * [#8704](https://github.com/rubocop-hq/rubocop/issues/8704): Fix an error for `Lint/AmbiguousOperator` when using safe navigation operator with a unary operator. ([@koic][])
 * [#8661](https://github.com/rubocop-hq/rubocop/pull/8661): Fix an incorrect auto-correct for `Style/MultilineTernaryOperator` when returning a multiline ternary operator expression. ([@koic][])
 * [#8526](https://github.com/rubocop-hq/rubocop/pull/8526): Fix a false positive for `Style/CaseEquality` cop when the receiver is not a camel cased constant. ([@koic][])
+* [#8673](https://github.com/rubocop-hq/rubocop/issues/8673): Fix the JSON parse error when specifying `--format=json` and `--stdin` options. ([@koic][])
 
 ### Changes
 
diff --git a/lib/rubocop/cli/command/execute_runner.rb b/lib/rubocop/cli/command/execute_runner.rb
index 9895c1650a9..f336981ef07 100644
--- a/lib/rubocop/cli/command/execute_runner.rb
+++ b/lib/rubocop/cli/command/execute_runner.rb
@@ -8,6 +8,9 @@ module Command
       class ExecuteRunner < Base
         include Formatter::TextUtil
 
+        # Combination of short and long formatter names.
+        INTEGRATION_FORMATTERS = %w[h html j json ju junit].freeze
+
         self.command_name = :execute_runner
 
         def run
@@ -61,6 +64,11 @@ def display_error_summary(errors)
         end
 
         def maybe_print_corrected_source
+          # Integration tools (like RubyMine) expect to have only the JSON result
+          # when specifying JSON format. Similar HTML and JUnit are targeted as well.
+          # See: https://github.com/rubocop-hq/rubocop/issues/8673
+          return if INTEGRATION_FORMATTERS.include?(@options[:format])
+
           # If we are asked to autocorrect source code read from stdin, the only
           # reasonable place to write it is to stdout
           # Unfortunately, we also write other information to stdout
diff --git a/spec/rubocop/cli/cli_options_spec.rb b/spec/rubocop/cli/cli_options_spec.rb
index 3ed5a4c5fc2..1d544d4344c 100644
--- a/spec/rubocop/cli/cli_options_spec.rb
+++ b/spec/rubocop/cli/cli_options_spec.rb
@@ -1719,6 +1719,36 @@ def f
       end
     end
 
+    it 'can parse JSON result when specifying `--format=json` and `--stdin` options' do
+      begin
+        $stdin = StringIO.new('p $/')
+        argv   = ['--auto-correct-all',
+                  '--only=Style/SpecialGlobalVars',
+                  '--format=json',
+                  '--stdin',
+                  'fake.rb']
+        expect(cli.run(argv)).to eq(0)
+        expect { JSON.parse($stdout.string) }.not_to raise_error(JSON::ParserError)
+      ensure
+        $stdin = STDIN
+      end
+    end
+
+    it 'can parse JSON result when specifying `--format=j` and `--stdin` options' do
+      begin
+        $stdin = StringIO.new('p $/')
+        argv   = ['--auto-correct-all',
+                  '--only=Style/SpecialGlobalVars',
+                  '--format=j',
+                  '--stdin',
+                  'fake.rb']
+        expect(cli.run(argv)).to eq(0)
+        expect { JSON.parse($stdout.string) }.not_to raise_error(JSON::ParserError)
+      ensure
+        $stdin = STDIN
+      end
+    end
+
     it 'detects CR at end of line' do
       begin
         create_file('example.rb', "puts 'hello world'\r")