From 71b97b6a382f11271d21acc94587b1e3e1168723 Mon Sep 17 00:00:00 2001
From: Kanezoh <asfaltmanta114@gmail.com>
Date: Thu, 27 May 2021 08:59:53 +0900
Subject: [PATCH] add runtime error

---
 src/mechanize.cr                                |  1 +
 src/mechanize/errors/base_error.cr              |  3 +++
 src/mechanize/errors/element_not_found_error.cr | 13 +++++++++++++
 src/mechanize/form.cr                           |  6 ++++--
 4 files changed, 21 insertions(+), 2 deletions(-)
 create mode 100644 src/mechanize/errors/base_error.cr
 create mode 100644 src/mechanize/errors/element_not_found_error.cr

diff --git a/src/mechanize.cr b/src/mechanize.cr
index dd4a30c..d1a8cd6 100644
--- a/src/mechanize.cr
+++ b/src/mechanize.cr
@@ -2,6 +2,7 @@ require "./mechanize/http/agent"
 require "./mechanize/form"
 require "./mechanize/node"
 require "./mechanize/page"
+require "./mechanize/errors/*"
 
 class Mechanize
   VERSION = "0.1.0"
diff --git a/src/mechanize/errors/base_error.cr b/src/mechanize/errors/base_error.cr
new file mode 100644
index 0000000..67be8ce
--- /dev/null
+++ b/src/mechanize/errors/base_error.cr
@@ -0,0 +1,3 @@
+# Base Error class
+class MechanizeCr::Error < RuntimeError
+end
diff --git a/src/mechanize/errors/element_not_found_error.cr b/src/mechanize/errors/element_not_found_error.cr
new file mode 100644
index 0000000..8d134b4
--- /dev/null
+++ b/src/mechanize/errors/element_not_found_error.cr
@@ -0,0 +1,13 @@
+require "./base_error"
+class MechanizeCr::ElementNotFoundError < MechanizeCr::Error
+  getter element : Symbol
+  getter conditions : String
+
+  def initialize(element, conditions)
+    @element    = element 
+    @conditions = conditions
+
+    super "Element #{element} with conditions #{conditions} was not found"
+  end
+  
+end
diff --git a/src/mechanize/form.cr b/src/mechanize/form.cr
index bd685a2..4034a9a 100644
--- a/src/mechanize/form.cr
+++ b/src/mechanize/form.cr
@@ -72,15 +72,17 @@ class MechanizeCr::Form
       # TODO
       # when args whose type isn't String is given
     end
-    fields.select do |field|
+    f = fields.select do |field|
       value.all? do |k,v|
         v === field.name
       end
     end
+    f.empty? ? nil : f
   end
 
   def field_with(criteria)
     f = fields_with(criteria)
-    f.empty? ? Array(MechanizeCr::FormContent::Field).new : f.first
+    raise MechanizeCr::ElementNotFoundError.new(:field, criteria) if f.nil?
+    f.first
   end
 end