Add option for verbose linting

This has come up a few times, and I can see why it might be helpful to
have access to full backtraces when debugging a factory error uncovered
by `FactoryBot.lint`. But since most of the time I don't want the extra
noise from the backtrace, I added this as a verbose option.

The default message is still:

```
The following factories are invalid:
* user - undefined method `save!' for #<User:0x00007ff0cbc89100>
* admin - undefined method `save!' for #<User:0x00007ff0cbc73e40>
```

And with the verbose option (usually with more lines of backtrace):

```
The following factories are invalid:
* user - undefined method `save!' for #<User:0x00007ff0cbc89100>
  /Users/.../thoughtbot/factory_bot/lib/factory_bot/evaluation.rb:18:in `create'
  /Users/.../factory_bot/lib/factory_bot/strategy/create.rb:12:in `block in result'

* admin - undefined method `save!' for #<User:0x00007ff0cbc73e40>
  /Users/.../thoughtbot/factory_bot/lib/factory_bot/evaluation.rb:18:in `create'
  /Users/.../factory_bot/lib/factory_bot/strategy/create.rb:12:in `block in result'
```

I moved the linting option defaults out of the FactoryBot.lint method
and into keyword argument defaults in Linter#initialize. This seems a
bit cleaner, and now we will get an error if we pass an option we don't
understand (before 6e511597 we had a test that passed in a bogus
option)

Closes #710
Closes #1124

I am opening a new PR since the original PR is years old and it seemed
unkind to request changes after so long. Instead I will list the authors
as co-authors.

Co-authored-by: Jack Kinsella <jack.kinsella@gmail.com>
Co-authored-by: Jasper Woudenberg <mail@jasperwoudenberg.com>

GETTING_STARTED.md

@@ -1110,6 +1110,13 @@ You can also specify the strategy used for linting:
 FactoryBot.lint strategy: :build
 ```
 
+Verbose linting will include full backtraces for each error, which can be
+helpful for debugging:
+
+```ruby
+FactoryBot.lint verbose: :true
+```
+
 Custom Construction
 -------------------
 

lib/factory_bot.rb

@@ -60,6 +60,7 @@ module FactoryBot
   # options:
   #   traits: true - to lint traits as well as factories
   #   strategy: :create - to specify the strategy for linting
+  #   verbose: true - to include full backtraces for each linting error
   def self.lint(*args)
     options = args.extract_options!
     factories_to_lint = args[0] || FactoryBot.factories

lib/factory_bot/linter.rb

@@ -1,9 +1,10 @@
 module FactoryBot
   class Linter
-    def initialize(factories, strategy: :create, traits: false)
+    def initialize(factories, strategy: :create, traits: false, verbose: false)
       @factories_to_lint = factories
       @factory_strategy = strategy
       @traits = traits
+      @verbose = verbose
       @invalid_factories = calculate_invalid_factories
     end
 
@@ -36,6 +37,13 @@ module FactoryBot
         "* #{location} - #{message} (#{@wrapped_error.class.name})"
       end
 
+      def verbose_message
+        <<~MESSAGE
+          #{message}
+            #{@wrapped_error.backtrace.join("\n  ")}
+        MESSAGE
+      end
+
       def location
         @factory.name
       end
@@ -85,7 +93,7 @@ module FactoryBot
 
     def error_message
       lines = invalid_factories.map do |_factory, exceptions|
-        exceptions.map(&:message)
+        exceptions.map(&error_message_type)
       end.flatten
 
       <<~ERROR_MESSAGE.strip
@@ -94,5 +102,13 @@ module FactoryBot
         #{lines.join("\n")}
       ERROR_MESSAGE
     end
+
+    def error_message_type
+      if @verbose
+        :verbose_message
+      else
+        :message
+      end
+    end
   end
 end

spec/acceptance/lint_spec.rb

@@ -176,4 +176,25 @@ describe "FactoryBot.lint" do
       end.not_to raise_error
     end
   end
+
+  describe "verbose linting" do
+    it "prints the backtrace for each factory error" do
+      define_class("InvalidThing") do
+        def save!
+          raise "invalid"
+        end
+      end
+
+      FactoryBot.define do
+        factory :invalid_thing
+      end
+
+      expect do
+        FactoryBot.lint(verbose: true)
+      end.to raise_error(
+        FactoryBot::InvalidFactoryError,
+        %r{#{__FILE__}:\d*:in `save!'},
+      )
+    end
+  end
 end