[custom-validation-messages]

.rubocop.yml

@@ -26,3 +26,8 @@ Style/RedundantBegin:
 # NOTE: too situative
 Metrics/ParameterLists:
   Enabled: false
+
+# Conflicts with current project style
+Style/NilComparison:
+  Enabled: true
+  EnforcedStyle: predicate

lib/qonfig/dsl.rb

@@ -72,7 +72,8 @@ def validators
   # @param predefined [String, Symbol]
   # @option by [String, Symbol, NilClass]
   # @option stict [Boolean]
-  # @param custom_validation [Proc]
+  # @option error_message [NilClass, String, Proc]
+  # @param custom_validation [Block]
   # @return [void]
   #
   # @see Qonfig::Validation::Building::InstanceBuilder
@@ -84,13 +85,15 @@ def validate(
     predefined = nil,
     strict: false,
     by: nil,
+    error_message: nil,
     &custom_validation
   )
     validators << Qonfig::Validation::Building::InstanceBuilder.build(
       self,
       setting_key_pattern: setting_key_pattern,
       predefined_validator: predefined,
       runtime_validation_method: by,
+      error_message: error_message,
       strict: strict,
       validation_logic: custom_validation
     )

lib/qonfig/validation/building/instance_builder.rb

@@ -35,11 +35,18 @@ class Qonfig::Validation::Building::InstanceBuilder
   # @since 0.17.0
   DEFAULT_STRICT_BEHAVIOUR = false
 
+  # @return [Boolean]
+  #
+  # @api private
+  # @since 0.26.0
+  DEFAULT_ERROR_MESSAGE = nil
+
   class << self
     # @param data_set_klass [Class<Qonfig::DataSet>]
     # @option setting_key_pattern [String, Symbol, NilClass]
     # @option predefined_validator [String, Symbol, NilClass]
     # @option runtime_validation_method [String, Symbol, NilClass]
+    # @option error_message [NilClass, String, Proc]
     # @option validation_logic [Proc, NilClass]
     # @option strict [Boolean]
     # @return [Qonfig::Validator::MethodBased, Qonfig::Validator::ProcBased]
@@ -50,6 +57,7 @@ def build(
       data_set_klass,
       setting_key_pattern: EMPTY_SETTING_KEY_PATTERN,
       runtime_validation_method: NO_RUNTIME_VALIDATION_METHOD,
+      error_message: DEFAULT_ERROR_MESSAGE,
       validation_logic: NO_VALIDATION_LOGIC,
       strict: DEFAULT_STRICT_BEHAVIOUR,
       predefined_validator: NO_PREDEFINED_VALIDATOR
@@ -59,6 +67,7 @@ def build(
         setting_key_pattern,
         predefined_validator,
         runtime_validation_method,
+        error_message,
         strict,
         validation_logic
       ).build
@@ -69,6 +78,7 @@ def build(
   # @param setting_key_pattern [String, Symbol, NilClass]
   # @param predefined_validator_name [String, Symbol, NilClass]
   # @param runtime_validation_method [String, Symbol, NilClass]
+  # @param error_message [NilClass, String, Proc]
   # @param strict [Boolean]
   # @param validation_logic [Proc, NilClass]
   # @return [void]
@@ -80,13 +90,15 @@ def initialize(
     setting_key_pattern,
     predefined_validator_name,
     runtime_validation_method,
+    error_message,
     strict,
     validation_logic
   )
     @data_set_klass = data_set_klass
     @setting_key_pattern = setting_key_pattern
     @predefined_validator_name = predefined_validator_name
     @runtime_validation_method = runtime_validation_method
+    @error_message = error_message
     @strict = strict
     @validation_logic = validation_logic
   end
@@ -140,6 +152,12 @@ def build
   # @since 0.20.0
   attr_reader :validation_logic
 
+  # @return [NilClass, String, Proc]
+  #
+  # @api private
+  # @since 0.26.0
+  attr_reader :error_message
+
   # @return [void]
   #
   # @raise [Qonfig::ArgumentError]
@@ -184,7 +202,7 @@ def build_setting_key_matcher
   # @since 0.20.0
   def build_method_based_validator
     Qonfig::Validation::Validators::MethodBased.new(
-      build_setting_key_matcher, strict, runtime_validation_method
+      build_setting_key_matcher, strict, runtime_validation_method, error_message
     )
   end
 
@@ -194,7 +212,7 @@ def build_method_based_validator
   # @since 0.20.0
   def build_proc_based_validator
     Qonfig::Validation::Validators::ProcBased.new(
-      build_setting_key_matcher, strict, validation_logic
+      build_setting_key_matcher, strict, validation_logic, error_message
     )
   end
 
@@ -213,7 +231,7 @@ def build_predefined_validator
       end
 
     Qonfig::Validation::Validators::Predefined.new(
-      build_setting_key_matcher, strict, predefined_validation_logic
+      build_setting_key_matcher, strict, predefined_validation_logic, error_message
     )
   end
 end

lib/qonfig/validation/validators/basic.rb

@@ -15,15 +15,23 @@ class Qonfig::Validation::Validators::Basic
   # @since 0.20.0
   attr_reader :strict
 
+  # @return [NilClass, String, Proc]
+  #
+  # @api private
+  # @since 0.26.0
+  attr_reader :error_message
+
   # @param setting_key_matcher [Qonfig::Settings::KeyMatcher, NilClass]
   # @param strict [Boolean]
+  # @param error_message [NilClass, String, Proc]
   # @return [void]
   #
   # @api private
   # @since 0.20.0
-  def initialize(setting_key_matcher, strict)
+  def initialize(setting_key_matcher, strict, error_message = nil)
     @setting_key_matcher = setting_key_matcher
     @strict = strict
+    @error_message = error_message
   end
 
   # @param data_set [Qonfig::DataSet]
@@ -58,4 +66,22 @@ def validate_full(data_set); end
   # @api private
   # @since 0.20.0
   def validate_concrete(data_set); end
+
+  # @param context [Object, NilClass]
+  # @return [String]
+  #
+  # @api private
+  # @since 0.26.0
+  def default_error_message(context); end
+
+  # @param context [Object, NilClass]
+  # @return [String]
+  #
+  # @api private
+  # @since 0.26.0
+  def build_error_message(context = nil)
+    return error_message.to_s if error_message.is_a?(String)
+    return error_message.call(context).to_s if error_message.respond_to?(:call)
+    default_error_message(context)
+  end
 end

lib/qonfig/validation/validators/method_based.rb

@@ -12,12 +12,13 @@ class Qonfig::Validation::Validators::MethodBased < Qonfig::Validation::Validato
   # @param setting_key_matcher [Qonfig::Settings::KeyMatcher, NilClass]
   # @param strict [Boolean]
   # @param runtime_validation_method [String, Symbol]
+  # @param error_message [NilClass, String, Proc]
   # @return [void]
   #
   # @api private
   # @since 0.20.0
-  def initialize(setting_key_matcher, strict, runtime_validation_method)
-    super(setting_key_matcher, strict)
+  def initialize(setting_key_matcher, strict, runtime_validation_method, error_message = nil)
+    super(setting_key_matcher, strict, error_message)
     @runtime_validation_method = runtime_validation_method
   end
 
@@ -33,7 +34,7 @@ def validate_concrete(data_set)
 
       raise(
         Qonfig::ValidationError,
-        "Invalid value of setting <#{setting_key}> (#{setting_value})"
+        build_error_message(setting_key: setting_key, setting_value: setting_value)
       ) unless data_set.__send__(runtime_validation_method, setting_value)
     end
   end
@@ -45,7 +46,17 @@ def validate_concrete(data_set)
   # @since 0.20.0
   def validate_full(data_set)
     unless data_set.__send__(runtime_validation_method)
-      raise(Qonfig::ValidationError, 'Invalid config object')
+      raise(Qonfig::ValidationError, build_error_message)
     end
   end
+
+  # @param context [Object, NilClass]
+  # @return [String]
+  #
+  # @api private
+  # @since 0.26.0
+  def default_error_message(context = nil)
+    return 'Invalid config object' if context.nil?
+    "Invalid value of setting <#{context[:setting_key]}> (#{context[:setting_value]})"
+  end
 end

lib/qonfig/validation/validators/predefined.rb

@@ -12,12 +12,13 @@ class Qonfig::Validation::Validators::Predefined < Qonfig::Validation::Validator
   # @param setting_key_matcher [Qonfig::Settings::KeyMatcher]
   # @param strict [Boolean]
   # @param validation [Proc]
+  # @param error_message [NilClass, String, Proc]
   # @return [void]
   #
   # @api private
   # @since 0.20.0
-  def initialize(setting_key_matcher, strict, validation)
-    super(setting_key_matcher, strict)
+  def initialize(setting_key_matcher, strict, validation, error_message = nil)
+    super(setting_key_matcher, strict, error_message)
     @validation = validation
   end
 
@@ -35,7 +36,7 @@ def validate_concrete(data_set)
 
       raise(
         Qonfig::ValidationError,
-        "Invalid value of setting <#{setting_key}> (#{setting_value})"
+        build_error_message(setting_key: setting_key, setting_value: setting_value)
       ) unless validation.call(setting_value)
     end
   end
@@ -52,4 +53,13 @@ def validate_full(data_set)
     raise Qonfig::Error, 'Predefined validator can be used with a setting key only'
     # :nocov:
   end
+
+  # @param context [Object, NilClass]
+  # @return [String]
+  #
+  # @api private
+  # @since 0.26.0
+  def default_error_message(context = nil)
+    "Invalid value of setting <#{context[:setting_key]}> (#{context[:setting_value]})"
+  end
 end

lib/qonfig/validation/validators/proc_based.rb

@@ -11,13 +11,14 @@ class Qonfig::Validation::Validators::ProcBased < Qonfig::Validation::Validators
 
   # @param setting_key_matcher [Qonfig::Settings::KeyMatcher, NilClass]
   # @param strict [Boolean]
-  # @param vaidation [Proc]
+  # @param validation [Proc]
+  # @param error_message [NilClass, String, Proc]
   # @return [void]
   #
   # @api private
   # @since 0.20.0
-  def initialize(setting_key_matcher, strict, validation)
-    super(setting_key_matcher, strict)
+  def initialize(setting_key_matcher, strict, validation, error_message = nil)
+    super(setting_key_matcher, strict, error_message)
     @validation = validation
   end
 
@@ -35,9 +36,10 @@ def validate_concrete(data_set)
 
       raise(
         Qonfig::ValidationError,
-        "Invalid value of setting <#{setting_key}> (#{setting_value})"
+        build_error_message(setting_key: setting_key, setting_value: setting_value)
       ) unless data_set.instance_exec(setting_value, &validation)
     end
+    false
   end
 
   # @param data_set [Qonfig::DataSet]
@@ -49,7 +51,17 @@ def validate_concrete(data_set)
   # @since 0.20.0
   def validate_full(data_set)
     unless data_set.instance_eval(&validation)
-      raise(Qonfig::ValidationError, 'Invalid config object')
+      raise(Qonfig::ValidationError, build_error_message)
     end
   end
+
+  # @param context [Object, NilClass]
+  # @return [String]
+  #
+  # @api private
+  # @since 0.26.0
+  def default_error_message(context = nil)
+    return 'Invalid config object' if context.nil?
+    "Invalid value of setting <#{context[:setting_key]}> (#{context[:setting_value]})"
+  end
 end