fix: validate response data inputs

Author: kholdrex

lib/irt_ruby.rb

@@ -2,6 +2,7 @@
 
 require "irt_ruby/version"
 require "matrix"
+require "irt_ruby/response_data_validator"
 require "irt_ruby/rasch_model"
 require "irt_ruby/two_parameter_model"
 require "irt_ruby/three_parameter_model"

lib/irt_ruby/rasch_model.rb

@@ -20,7 +20,7 @@ def initialize(data,
       # missing_strategy: :ignore (skip), :treat_as_incorrect, :treat_as_correct
 
       @data = data
-      @data_array = data.to_a
+      @data_array = ResponseDataValidator.validate!(data)
       num_rows = @data_array.size
       num_cols = @data_array.first.size
 

lib/irt_ruby/response_data_validator.rb

@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+module IrtRuby
+  # Validates response data accepted by IRT model constructors.
+  module ResponseDataValidator
+    VALID_RESPONSES = [0, 1, nil].freeze
+
+    module_function
+
+    def validate!(data)
+      raise ArgumentError, "response data must be a Matrix or array of arrays" unless data.respond_to?(:to_a)
+
+      data_array = data.to_a
+
+      raise ArgumentError, "response data must have at least one row" unless data_array.is_a?(Array) && data_array.any?
+
+      validate_rows!(data_array)
+      validate_values!(data_array)
+
+      data_array
+    end
+
+    def validate_rows!(data_array)
+      first_row = data_array.first
+
+      raise ArgumentError, "response data must be a Matrix or array of arrays" unless first_row.is_a?(Array)
+
+      expected_columns = first_row.size
+      raise ArgumentError, "response data must have at least one column" if expected_columns.zero?
+
+      data_array.each_with_index do |row, index|
+        raise ArgumentError, "response data row #{index} must be an Array" unless row.is_a?(Array)
+
+        next if row.size == expected_columns
+
+        raise ArgumentError, "response data must be rectangular; row #{index} has #{row.size} columns, expected #{expected_columns}"
+      end
+    end
+
+    def validate_values!(data_array)
+      data_array.each_with_index do |row, row_index|
+        row.each_with_index do |value, column_index|
+          next if VALID_RESPONSES.include?(value)
+
+          raise ArgumentError,
+                "response data contains invalid value #{value.inspect} at row #{row_index}, column #{column_index}; allowed values are 0, 1, and nil"
+        end
+      end
+    end
+  end
+end

lib/irt_ruby/three_parameter_model.rb

@@ -19,7 +19,7 @@ def initialize(data,
                    decay_factor: 0.5,
                    missing_strategy: :ignore)
       @data = data
-      @data_array = data.to_a
+      @data_array = ResponseDataValidator.validate!(data)
       num_rows = @data_array.size
       num_cols = @data_array.first.size
 

lib/irt_ruby/two_parameter_model.rb

@@ -15,7 +15,7 @@ def initialize(data, max_iter: 1000, tolerance: 1e-6, param_tolerance: 1e-6,
                    learning_rate: 0.01, decay_factor: 0.5,
                    missing_strategy: :ignore)
       @data = data
-      @data_array = data.to_a
+      @data_array = ResponseDataValidator.validate!(data)
       num_rows = @data_array.size
       num_cols = @data_array.first.size
 

spec/irt_ruby/rasch_model_spec.rb

@@ -3,6 +3,8 @@
 require "spec_helper"
 
 RSpec.describe IrtRuby::RaschModel do
+  it_behaves_like "response data validation"
+
   let(:data_array) do
     [
       [1, 1, 0],

spec/irt_ruby/three_parameter_model_spec.rb

@@ -3,6 +3,8 @@
 require "spec_helper"
 
 RSpec.describe IrtRuby::ThreeParameterModel do
+  it_behaves_like "response data validation"
+
   let(:data_array) do
     [
       [1, 1, 0],

spec/irt_ruby/two_parameter_model_spec.rb

@@ -3,6 +3,8 @@
 require "spec_helper"
 
 RSpec.describe IrtRuby::TwoParameterModel do
+  it_behaves_like "response data validation"
+
   let(:data_array) do
     [
       [1, 1, 0],

spec/spec_helper.rb

@@ -2,6 +2,28 @@
 
 require "irt_ruby"
 
+RSpec.shared_examples "response data validation" do
+  it "rejects empty data" do
+    expect { described_class.new([]) }.to raise_error(ArgumentError, /at least one row/)
+  end
+
+  it "rejects empty rows" do
+    expect { described_class.new([[]]) }.to raise_error(ArgumentError, /at least one column/)
+  end
+
+  it "rejects ragged rows" do
+    expect { described_class.new([[1, 0], [1]]) }.to raise_error(ArgumentError, /rectangular/)
+  end
+
+  it "rejects invalid response values" do
+    expect { described_class.new([[1, 2], [0, nil]]) }.to raise_error(ArgumentError, /invalid value 2/)
+  end
+
+  it "rejects non-numeric truthy, falsey, and string responses" do
+    expect { described_class.new([[1, "1"], [false, nil]]) }.to raise_error(ArgumentError, /invalid value/)
+  end
+end
+
 RSpec.configure do |config|
   # Enable flags like --only-failures and --next-failure
   config.example_status_persistence_file_path = ".rspec_status"