Add validation for chronic_duration_attr_writer

app/models/concerns/chronic_duration_attribute.rb

@@ -18,13 +18,32 @@ module ChronicDurationAttribute
     end
 
     def chronic_duration_attr_writer(virtual_attribute, source_attribute)
+      virtual_attribute_validator = "#{virtual_attribute}_validator".to_sym
+      validation_error = "#{virtual_attribute}_error".to_sym
+
+      validate virtual_attribute_validator
+      attr_accessor validation_error
+
       define_method("#{virtual_attribute}=") do |value|
-        new_value = ChronicDuration.parse(value).to_i unless value.nil?
-        new_value = nil if !new_value.nil? && new_value <= 0
+        begin
+          self.send("#{validation_error}=", '') # rubocop:disable GitlabSecurity/PublicSend
+
+          new_value =
+            if value.blank?
+              nil
+            else
+              ChronicDuration.parse(value).to_i
+            end
 
           self.send("#{source_attribute}=", new_value) # rubocop:disable GitlabSecurity/PublicSend
+        rescue ChronicDuration::DurationParseError => ex
+          self.send("#{validation_error}=", ex.message) # rubocop:disable GitlabSecurity/PublicSend
+        end
+      end
 
-        new_value
+      define_method(virtual_attribute_validator) do
+        error = self.send(validation_error) # rubocop:disable GitlabSecurity/PublicSend
+        self.send('errors').add(source_attribute, error) unless error.blank? # rubocop:disable GitlabSecurity/PublicSend
       end
     end
   end

spec/models/concerns/chronic_duration_attribute_spec.rb

@@ -11,11 +11,13 @@ shared_examples 'ChronicDurationAttribute reader' do
     expect(subject.send(virtual_field)).to eq('2m')
   end
 
-  it 'outputs empty string when value set to nil' do
+  context 'when value is set to nil' do
+    it 'outputs empty string' do
       subject.send("#{source_field}=", nil)
 
       expect(subject.send(virtual_field)).to be_empty
     end
+  end
 end
 
 shared_examples 'ChronicDurationAttribute writer' do
@@ -29,29 +31,63 @@ shared_examples 'ChronicDurationAttribute writer' do
     expect(subject.send(source_field)).to eq(600)
   end
 
-  it 'writes nil when empty input is used' do
-    subject.send("#{virtual_field}=", '')
+  it 'passes validation' do
+    subject.send("#{virtual_field}=", '10m')
 
-    expect(subject.send(source_field)).to be_nil
+    expect(subject.valid?).to be_truthy
+  end
+
+  context 'when negative input is used' do
+    before do
+      subject.send("#{source_field}=", 3600)
     end
 
-  it 'writes nil when negative input is used' do
-    allow(ChronicDuration).to receive(:parse).and_return(-10)
+    it "doesn't raise exception" do
+      expect { subject.send("#{virtual_field}=", '-10m') }.not_to raise_error(ChronicDuration::DurationParseError)
+    end
+
+    it "doesn't change value" do
+      expect { subject.send("#{virtual_field}=", '-10m') }.not_to change { subject.send(source_field) }
+    end
 
+    it "doesn't pass validation" do
       subject.send("#{virtual_field}=", '-10m')
 
+      expect(subject.valid?).to be_falsey
+    end
+  end
+
+  context 'when empty input is used' do
+    it 'writes nil' do
+      subject.send("#{virtual_field}=", '')
+
       expect(subject.send(source_field)).to be_nil
     end
 
-  it 'writes nil when nil input is used' do
+    it 'passes validation' do
+      subject.send("#{virtual_field}=", '')
+
+      expect(subject.valid?).to be_truthy
+    end
+  end
+
+  context 'when nil input is used' do
+    it 'writes nil' do
       subject.send("#{virtual_field}=", nil)
 
       expect(subject.send(source_field)).to be_nil
     end
 
-  it "doesn't raise exception when nil input is used" do
+    it 'passes validation' do
+      subject.send("#{virtual_field}=", nil)
+
+      expect(subject.valid?).to be_truthy
+    end
+
+    it "doesn't raise exception" do
       expect { subject.send("#{virtual_field}=", nil) }.not_to raise_error(NoMethodError)
     end
+  end
 end
 
 describe 'ChronicDurationAttribute' do