add exec CLI command for auto instrumentation

exe/ddcirb

@@ -2,4 +2,6 @@
 
 require "datadog/ci/cli/cli"
 
-Datadog::CI::CLI.exec(ARGV.first)
+command = ARGV.shift
+
+Datadog::CI::CLI.exec(command, ARGV)

lib/datadog/ci/cli/cli.rb

@@ -1,14 +1,17 @@
 require "datadog"
 require "datadog/ci"
 
+require_relative "command/exec"
 require_relative "command/skippable_tests_percentage"
 require_relative "command/skippable_tests_percentage_estimate"
 
 module Datadog
   module CI
     module CLI
-      def self.exec(action)
+      def self.exec(action, args = [])
         case action
+        when "exec"
+          Command::Exec.new(args).exec
         when "skipped-tests", "skippable-tests"
           Command::SkippableTestsPercentage.new.exec
         when "skipped-tests-estimate", "skippable-tests-estimate"
@@ -17,6 +20,7 @@ def self.exec(action)
           puts("Usage: bundle exec ddcirb [command] [options]. Available commands:")
           puts("  skippable-tests - calculates the exact percentage of skipped tests and prints it to stdout or file")
           puts("  skippable-tests-estimate - estimates the percentage of skipped tests and prints it to stdout or file")
+          puts("  exec YOUR_TEST_COMMAND - automatically instruments your test command with Datadog and executes it")
         end
       end
     end

lib/datadog/ci/cli/command/exec.rb

@@ -0,0 +1,29 @@
+require_relative "base"
+require_relative "../../test_optimisation/skippable_percentage/estimator"
+
+module Datadog
+  module CI
+    module CLI
+      module Command
+        class Exec < Base
+          def initialize(args)
+            super()
+
+            @args = args
+          end
+
+          def exec
+            rubyopts = [
+              "-rdatadog/ci/auto_instrument"
+            ]
+
+            existing_rubyopt = ENV["RUBYOPT"]
+            ENV["RUBYOPT"] = existing_rubyopt ? "#{existing_rubyopt} #{rubyopts.join(" ")}" : rubyopts.join(" ")
+
+            Kernel.exec(*@args)
+          end
+        end
+      end
+    end
+  end
+end

sig/datadog/ci/cli/cli.rbs

@@ -1,7 +1,7 @@
 module Datadog
   module CI
     module CLI
-      def self.exec: (String action) -> void
+      def self.exec: (String action, ?Array[String] args) -> void
     end
   end
 end

sig/datadog/ci/cli/command/exec.rbs

@@ -0,0 +1,15 @@
+module Datadog
+  module CI
+    module CLI
+      module Command
+        class Exec < Base
+          @args: Array[String]
+
+          def initialize: (Array[String] args) -> void
+
+          def exec: () -> void
+        end
+      end
+    end
+  end
+end

spec/datadog/ci/cli/cli_spec.rb

@@ -36,6 +36,7 @@
           Usage: bundle exec ddcirb [command] [options]. Available commands:
             skippable-tests - calculates the exact percentage of skipped tests and prints it to stdout or file
             skippable-tests-estimate - estimates the percentage of skipped tests and prints it to stdout or file
+            exec YOUR_TEST_COMMAND - automatically instruments your test command with Datadog and executes it
         USAGE
       end
     end