Add option to suppress diff output

Signed-off-by: Clinton Wolfe <clintoncwolfe@gmail.com>

lib/inspec/base_cli.rb

@@ -158,6 +158,8 @@ module Inspec
       option :silence_deprecations, type: :array,
         banner: "[all]|[GROUP GROUP...]",
         desc: "Suppress deprecation warnings. See install_dir/etc/deprecations.json for list of GROUPs or use 'all'."
+      option :diff, type: :boolean, default: true,
+        desc: "Use --no-diff to suppress 'diff' output of failed textual test results."
     end
 
     def self.format_platform_info(params: {}, indent: 0, color: 39)

lib/inspec/utils/run_data_filters.rb

@@ -14,6 +14,7 @@ module Inspec
         @config[:runtime_config] = Inspec::Config.cached || {}
         apply_report_resize_options
         redact_sensitive_inputs
+        suppress_diff_output
       end
 
       # Apply options such as message truncation and removal of backtraces
@@ -45,6 +46,24 @@ module Inspec
         end
       end
 
+      # Optionally suppress diff output in the message field
+      def suppress_diff_output
+        return if @config[:runtime_config][:diff]
+
+        @run_data[:profiles]&.each do |p|
+          p[:controls]&.each do |c|
+            c[:results]&.each do |r|
+              next unless r[:message] # :message only set on failure
+
+              pos = r[:message].index("\n\nDiff:")
+              next unless pos # Only textual tests get Diffs
+
+              r[:message] = r[:message].slice(0, pos)
+            end
+          end
+        end
+      end
+
       private
 
       def process_message_truncation(result)

test/fixtures/profiles/diff-output/controls/diff-output.rb

@@ -0,0 +1,30 @@
+control "no-diff" do
+  expected = 1 + 1
+  actual = 2
+  describe expected do
+    it { should eq actual }
+  end
+end
+
+control "text-diff" do
+  expected = <<~EOT
+I am the very
+model of a modern
+major general
+EOT
+  # No one expects this
+  actual = <<~EOT
+The Spanish Inquisition
+EOT
+  describe expected do
+    it { should eq actual }
+  end
+end
+
+control "array-diff" do
+  expected = [1,2,3,4]
+  actual = [5,6,7]
+  describe expected do
+    it { should eq actual }
+  end
+end

test/fixtures/profiles/diff-output/inspec.yml

@@ -0,0 +1,10 @@
+name: diff-output
+title: InSpec Profile
+maintainer: The Authors
+copyright: The Authors
+copyright_email: you@example.com
+license: Apache-2.0
+summary: An InSpec Compliance Profile
+version: 0.1.0
+supports:
+  platform: os

test/functional/inspec_exec_json_test.rb

@@ -356,4 +356,32 @@ describe "inspec exec with json formatter" do
       _(failed_result["backtrace"]).must_be :nil?
     end
   end
+
+  describe "JSON reporter using the --diff/--no-diff options" do
+    describe "JSON reporter with --diff option" do
+      let(:run_result) { run_inspec_process("exec #{profile_path}/diff-output --diff", json: true) }
+      let(:controls) { @json["profiles"][0]["controls"] }
+      it "runs normally with --diff" do
+        _(run_result.stderr).must_be_empty
+        _(controls[1]["results"][0]["message"]).must_include "got:"
+        _(controls[1]["results"][0]["message"]).must_include "Diff:"
+        _(controls[2]["results"][0]["message"]).must_include "got:"
+        assert_exit_code(100, run_result)
+      end
+    end
+
+    describe "JSON reporter with --no-diff option" do
+      let(:run_result) { run_inspec_process("exec #{profile_path}/diff-output --no-diff", json: true) }
+      let(:controls) { @json["profiles"][0]["controls"] }
+      it "suppresses the diff" do
+        _(run_result.stderr).must_be_empty
+        _(controls[1]["results"][0]["message"]).must_include "got:"
+        _(controls[1]["results"][0]["message"]).wont_include "Diff:"
+        _(controls[1]["results"][0]["message"]).wont_include "vegetable"
+        _(controls[2]["results"][0]["message"]).must_include "got:" # non-textual tests don't do diffs
+        assert_exit_code(100, run_result)
+      end
+    end
+  end
+
 end