[thin_check] Start refactoring metadata_checker.

features/step_definitions/thin_steps.rb

@@ -7,7 +7,20 @@ Given(/^valid metadata$/) do
   run_simple("thin_restore -i #{xml_file} -o #{dev_file}")
 end
 
-When(/^I run thin_check with (.*?)$/) do |opts|
-  run "thin_check #{opts} #{dev_file}"
+Given(/^a corrupt superblock$/) do
+  in_current_dir do
+    write_valid_xml(xml_file)
+  end
+
+  run_simple("dd if=/dev/zero of=#{dev_file} bs=4k count=1024")
+  run_simple("thin_restore -i #{xml_file} -o #{dev_file}")
+
+  in_current_dir do
+    corrupt_block(0)
+  end
+end
+
+When(/^I run thin_check with (.*?)$/) do |opts|
+  run_simple("thin_check #{opts} #{dev_file}", false)
 end
 

features/support/world_extensions.rb

@@ -11,6 +11,10 @@ module ThinpWorld
     'metadata.bin'
   end
 
+  def corrupt_block(n)
+    write_block(n, change_random_byte(read_block(n)))
+  end
+
   # FIXME: we should really break out the xml stuff from
   # thinp-test-suite and put in a gem in this repo.
   def write_valid_xml(path)
@@ -24,6 +28,32 @@ module ThinpWorld
 EOF
     end
   end
+
+  private
+  def read_block(n)
+    b = nil
+
+    File.open(dev_file, "r") do |f|
+      f.seek(n * 4096)
+      b = f.read(4096)
+    end
+
+    b
+  end
+
+  def write_block(n, b)
+    File.open(dev_file, "w") do |f|
+      f.seek(n * 4096)
+      f.write(b)
+    end
+  end
+
+  def change_random_byte(b)
+    i = rand(b.size)
+    puts "changing byte #{i}"
+    b.setbyte(i, (b.getbyte(i) + 1) % 256)
+    b
+  end
 end
 
 World(ThinpWorld)

features/thin_check.feature

@@ -40,8 +40,17 @@ Feature: thin_check
       {--super-block-only}
     """
 
-  @announce
+  Scenario: Unrecognised option should cause failure
+    When I run `thin_check --hedeghogs-only`
+    Then it should fail
+
   Scenario: --super-block-only check passes on valid metadata
     Given valid metadata
     When I run thin_check with --super-block-only
-    Then it should pass
+    Then it should pass
+
+  @announce
+  Scenario: --super-block-only check fails with corrupt superblock
+    Given a corrupt superblock
+    When I run thin_check with --super-block-only
+    Then it should fail