feat: better error handling

Author: vicentereig

.rspec_status

@@ -1,20 +1,21 @@
 example_id                                    | status | run_time        |
 --------------------------------------------- | ------ | --------------- |
-./spec/dspy/chain_of_thought_spec.rb[1:1:1]   | passed | 0.04216 seconds |
-./spec/dspy/chain_of_thought_spec.rb[1:1:2]   | passed | 0.00218 seconds |
-./spec/dspy/colbertv2_rag_spec.rb[1:1]        | passed | 0.00095 seconds |
-./spec/dspy/colbertv2_rag_spec.rb[1:2]        | passed | 0.00295 seconds |
-./spec/dspy/ext/dry_schema_ext_spec.rb[1:1]   | passed | 0.00091 seconds |
-./spec/dspy/ext/dry_schema_ext_spec.rb[1:2]   | passed | 0.00007 seconds |
-./spec/dspy/ext/dry_schema_ext_spec.rb[1:3]   | passed | 0.00109 seconds |
-./spec/dspy/ext/dry_schema_ext_spec.rb[1:4]   | passed | 0.00008 seconds |
-./spec/dspy/multi_stage_pipeline_spec.rb[1:1] | passed | 0.00207 seconds |
-./spec/dspy/multi_stage_pipeline_spec.rb[1:2] | passed | 0.00164 seconds |
-./spec/dspy/multi_stage_pipeline_spec.rb[1:3] | passed | 0.00417 seconds |
-./spec/dspy/multi_stage_pipeline_spec.rb[1:4] | passed | 0.00632 seconds |
-./spec/dspy/predict_spec.rb[1:1:1]            | passed | 0.0016 seconds  |
-./spec/dspy/predict_spec.rb[1:1:2]            | passed | 0.00161 seconds |
+./spec/dspy/chain_of_thought_spec.rb[1:1:1]   | passed | 0.02183 seconds |
+./spec/dspy/chain_of_thought_spec.rb[1:1:2]   | passed | 0.00196 seconds |
+./spec/dspy/colbertv2_rag_spec.rb[1:1]        | passed | 0.00097 seconds |
+./spec/dspy/colbertv2_rag_spec.rb[1:2]        | passed | 0.0029 seconds  |
+./spec/dspy/ext/dry_schema_ext_spec.rb[1:1]   | passed | 0.00101 seconds |
+./spec/dspy/ext/dry_schema_ext_spec.rb[1:2]   | passed | 0.00006 seconds |
+./spec/dspy/ext/dry_schema_ext_spec.rb[1:3]   | passed | 0.00104 seconds |
+./spec/dspy/ext/dry_schema_ext_spec.rb[1:4]   | passed | 0.00009 seconds |
+./spec/dspy/multi_stage_pipeline_spec.rb[1:1] | passed | 0.00361 seconds |
+./spec/dspy/multi_stage_pipeline_spec.rb[1:2] | passed | 0.00173 seconds |
+./spec/dspy/multi_stage_pipeline_spec.rb[1:3] | passed | 0.00429 seconds |
+./spec/dspy/multi_stage_pipeline_spec.rb[1:4] | passed | 0.00631 seconds |
+./spec/dspy/predict_spec.rb[1:1:1]            | passed | 0.00183 seconds |
+./spec/dspy/predict_spec.rb[1:1:2]            | passed | 0.00318 seconds |
+./spec/dspy/predict_validation_spec.rb[1:1:1] | passed | 0.00302 seconds |
 ./spec/dspy/signature_spec.rb[1:1]            | passed | 0.00006 seconds |
 ./spec/dspy/signature_spec.rb[1:2]            | passed | 0.00005 seconds |
-./spec/dspy_spec.rb[1:1:1]                    | passed | 0.00045 seconds |
-./spec/dspy_spec.rb[1:1:2]                    | passed | 0.00004 seconds |
+./spec/dspy_spec.rb[1:1:1]                    | passed | 0.00031 seconds |
+./spec/dspy_spec.rb[1:1:2]                    | passed | 0.00003 seconds |

lib/dspy/predict.rb

@@ -1,6 +1,13 @@
 # frozen_string_literal: true
 
 module DSPy
+  class PredictionInvalidError < RuntimeError
+    attr_accessor :errors
+    def initialize(errors)
+      @errors = errors
+      super("Prediction invalid")
+    end
+  end
   class Predict < DSPy::Module
     attr_reader :signature_class
 
@@ -59,8 +66,7 @@ def forward(**input_values)
         poro_class = Data.define(*output_attributes.keys)
         return poro_class.new(*output_attributes.values)
       end
-
-      raise result.errors
+      raise PredictionInvalidError, result.errors
     end
   end
 end

spec/dspy/predict_validation_spec.rb

@@ -0,0 +1,33 @@
+require 'spec_helper'
+
+RSpec.describe DSPy::Predict do
+  before do
+    DSPy.configure do |c|
+      c.lm = DSPy::LM.new('openai/gpt-4o-mini', api_key: ENV['OPENAI_API_KEY'])
+    end
+  end
+
+  describe 'sentiment classification example' do
+    it 'raises an exception when sending wrong params' do
+      VCR.use_cassette('openai/gpt4o-mini/predict_validation') do
+        class Classify < DSPy::Signature
+          description "Classify sentiment of a given sentence."
+
+          input do
+            required(:sentence).value(:string).meta(description: 'The sentence whose sentiment you are analyzing')
+          end
+
+          output do
+            required(:sentiment).value(included_in?: %w(positive negative neutral))
+                                .meta(description: 'The allowed values to classify sentences')
+            required(:confidence).value(:float).meta(description: 'The confidence score for the classification')
+          end
+        end
+        # Create the predictor
+        @classify = DSPy::Predict.new(Classify)
+
+        expect { @classify.call(sentence: 1337) }.to raise_error(DSPy::PredictionInvalidError)
+      end
+    end
+  end
+end