feat(backup-monitor): implement PayloadBuilder with tests

scripts/notify_backup.rb

@@ -56,6 +56,33 @@ class ByteFormatter
 end
 
 class PayloadBuilder
+  VALID_STATUSES = %w[success failure skipped].freeze
+
+  def initialize(options)
+    @options = options
+  end
+
+  def build
+    validate!
+    {
+      timestamp:         Time.now.utc.strftime('%Y-%m-%dT%H:%M:%SZ'),
+      machine:           @options[:machine],
+      destination:       @options[:destination],
+      status:            @options[:status],
+      bytes_transferred: ByteFormatter.format(@options[:bytes]),
+      snapshot_id:       @options[:snapshot],
+      log_path:          @options[:log_path],
+      notes:             @options[:notes]
+    }.compact
+  end
+
+  private
+
+  def validate!
+    return if VALID_STATUSES.include?(@options[:status])
+
+    raise ArgumentError, "status must be one of: #{VALID_STATUSES.join(', ')}"
+  end
 end
 
 class WebhookClient

scripts/notify_backup_test.rb

@@ -29,3 +29,54 @@ class ByteFormatterTest < Minitest::Test
     assert_equal '1.00 GB', ByteFormatter.format('1073741824')
   end
 end
+
+class PayloadBuilderTest < Minitest::Test
+  def base_options
+    { machine: 'desktop', destination: 'synology', status: 'success' }
+  end
+
+  def test_builds_required_fields
+    payload = PayloadBuilder.new(base_options).build
+    assert_equal 'desktop', payload[:machine]
+    assert_equal 'synology', payload[:destination]
+    assert_equal 'success', payload[:status]
+    assert_match(/\A\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}Z\z/, payload[:timestamp])
+  end
+
+  def test_formats_bytes_to_human_readable
+    payload = PayloadBuilder.new(base_options.merge(bytes: 1_073_741_824)).build
+    assert_equal '1.00 GB', payload[:bytes_transferred]
+  end
+
+  def test_omits_nil_optional_fields
+    payload = PayloadBuilder.new(base_options).build
+    refute payload.key?(:bytes_transferred)
+    refute payload.key?(:snapshot_id)
+    refute payload.key?(:log_path)
+    refute payload.key?(:notes)
+  end
+
+  def test_includes_all_optional_fields_when_present
+    opts = base_options.merge(
+      bytes: 1_048_576,
+      snapshot: 'abc12345',
+      log_path: '/home/jared/.local/log/restic/2026-05-07.log',
+      notes: 'snapshot abc12345 saved'
+    )
+    payload = PayloadBuilder.new(opts).build
+    assert_equal '1.00 MB',    payload[:bytes_transferred]
+    assert_equal 'abc12345',   payload[:snapshot_id]
+    assert_equal '/home/jared/.local/log/restic/2026-05-07.log', payload[:log_path]
+    assert_equal 'snapshot abc12345 saved', payload[:notes]
+  end
+
+  def test_raises_on_invalid_status
+    assert_raises(ArgumentError) { PayloadBuilder.new(base_options.merge(status: 'unknown')).build }
+  end
+
+  def test_all_valid_statuses_accepted
+    %w[success failure skipped].each do |s|
+      assert PayloadBuilder.new(base_options.merge(status: s)).build
+    end
+  end
+end