Add support for CSV content from stdin in CLI

README.md

@@ -508,13 +508,28 @@ Alternatively, you can run your Task in the command line:
 bundle exec maintenance_tasks perform Maintenance::UpdatePostsTask
 ```
 
-To run a Task that processes CSVs from the command line, use the --csv option:
+To run a Task that processes CSVs from the command line, use the `--csv` option:
 
 ```sh-session
 bundle exec maintenance_tasks perform Maintenance::ImportPostsTask --csv "path/to/my_csv.csv"
 ```
 
-To run a Task that takes arguments from the command line, use the --arguments
+The `--csv` option also works with CSV content coming from the standard input:
+
+```sh-session
+curl "some/remote/csv" | bundle exec maintenance_tasks perform Maintenance::ImportPostsTask --csv
+```
+
+Or even typed inline:
+
+```sh-session
+bundle exec maintenance_tasks perform Maintenance::ImportPostsTask --csv -
+foo,bar,baz
+1,2,3
+^D
+```
+
+To run a Task that takes arguments from the command line, use the `--arguments`
 option, passing arguments as a set of \<key>:\<value> pairs:
 
 ```sh-session

lib/maintenance_tasks/cli.rb

@@ -1,5 +1,6 @@
 # frozen_string_literal: true
 
+require "stringio"
 require "thor"
 
 module MaintenanceTasks
@@ -53,9 +54,15 @@ def perform(name)
 
     def csv_file
       csv_option = options[:csv]
-      if csv_option
+      return unless csv_option.present?
+
+      if csv_option == "-" || !$stdin.tty?
+        { io: StringIO.new($stdin.read), filename: File.basename("stdin.csv") }
+      else
         { io: File.open(csv_option), filename: File.basename(csv_option) }
       end
+    rescue Errno::ENOENT
+      raise ArgumentError, "CSV file not found or specified."
     end
   end
 end

test/lib/maintenance_tasks/cli_test.rb

@@ -48,6 +48,49 @@ class CLITest < ActiveSupport::TestCase
       @cli.perform("MyCsvTask")
     end
 
+    test "#perform runs a CSV Task with the CSV from stdin when --csv option used" do
+      task = mock(name: "MyCsvTask")
+      csv_string = "foo,bar\n1,2\n"
+      actual_stdin = $stdin
+      $stdin = StringIO.new(csv_string)
+
+      csv_string_io = StringIO.new(csv_string)
+      expected_attachable = { io: csv_string_io, filename: "stdin.csv" }
+
+      # 'csv' is the fallback value Thor uses when you don't supply any.
+      @cli.expects(:options).at_least_once.returns(csv: "csv")
+      StringIO.expects(:new).with(csv_string).returns(csv_string_io)
+      Runner.expects(:run)
+        .with(name: "MyCsvTask", csv_file: expected_attachable, arguments: {})
+        .returns(task)
+      @cli.expects(:say_status)
+        .with(:success, "MyCsvTask was enqueued.", :green)
+
+      @cli.perform("MyCsvTask")
+
+      $stdin = actual_stdin
+    end
+
+    test "#perform prints an error message when no CSV file is provided to --csv option" do
+      # 'csv' is the fallback value Thor uses when you don't supply any.
+      @cli.expects(:options).at_least_once.returns(csv: "csv")
+      @cli.expects(:say_status)
+        .with(:error, "CSV file not found or specified.", :red)
+
+      @cli.perform("MyCsvTask")
+    end
+
+    test "#perform prints an error message when provided CSV file does not exist" do
+      bad_csv_file_path = "foo.csv"
+      # 'csv' is the fallback value Thor uses when you don't supply any.
+      @cli.expects(:options).at_least_once.returns(csv: bad_csv_file_path)
+      File.expects(:open).with(bad_csv_file_path).raises(Errno::ENOENT)
+      @cli.expects(:say_status)
+        .with(:error, "CSV file not found or specified.", :red)
+
+      @cli.perform("MyCsvTask")
+    end
+
     test "#perform runs a Task with the supplied arguments when --arguments option used" do
       task = mock(name: "MyParamsTask")
       arguments = { "post_ids": "1,2,3" }