Skip partial indexes and conditional validators in uniqueness checkers (#277)

Author: Copilot

.gitignore

@@ -6,6 +6,7 @@
 /pkg/
 /spec/reports/
 /tmp/
+/vendor/bundle/
 
 # rspec failure tracking
 .rspec_status

CHANGELOG.md

@@ -1,5 +1,10 @@
 # Changelog
 
+### [Unreleased]
+
+- Fix `UniqueIndexChecker` to skip partial indexes (indexes with a `WHERE` clause).
+- Fix `MissingUniqueIndexChecker` to skip uniqueness validators with a `conditions` option.
+
 ### [2.1.3] - 2026/02/20
 
 - Fix `MissingDependentDestroyChecker` to support composite keys. Thanks [Andy Allan](https://github.com/gravitystorm) for reporting this! 

lib/database_consistency/checkers/index_checkers/unique_index_checker.rb

@@ -8,8 +8,9 @@ class UniqueIndexChecker < IndexChecker
 
       # We skip check when:
       #  - index is not unique
+      #  - index is a partial index (has a where clause)
       def preconditions
-        index.unique
+        index.unique && index.where.nil?
       end
 
       # Table of possible statuses

lib/database_consistency/checkers/validator_checkers/missing_unique_index_checker.rb

@@ -18,8 +18,9 @@ def column_or_attribute_name
 
       # We skip check when:
       #  - validator is not a uniqueness validator
+      #  - validator has a conditions option (partial validation, may correspond to partial index)
       def preconditions
-        validator.kind == :uniqueness
+        validator.kind == :uniqueness && validator.options[:conditions].nil?
       end
 
       # Table of possible statuses

spec/checkers/missing_unique_index_checker_spec.rb

@@ -272,4 +272,24 @@
       end
     end
   end
+
+  context 'when uniqueness validation has conditions option' do
+    let(:attribute) { :account_id }
+    let(:klass) do
+      define_class do |klass|
+        klass.validates :account_id, uniqueness: { conditions: -> { where(is_default: true) } }
+      end
+    end
+
+    before do
+      define_database_with_entity do |table|
+        table.integer :account_id
+        table.boolean :is_default
+      end
+    end
+
+    specify do
+      expect(checker.report).to be_nil
+    end
+  end
 end

spec/checkers/unique_index_checker/postgresql_spec.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+RSpec.describe DatabaseConsistency::Checkers::UniqueIndexChecker, :postgresql do
+  subject(:checker) { described_class.new(model, index) }
+
+  let(:model) { klass }
+  let(:index) { ActiveRecord::Base.connection.indexes(klass.table_name).first }
+
+  let(:index_name) { 'index_name' }
+
+  context 'when unique partial index exists' do
+    before do
+      define_database_with_entity do |table|
+        table.integer :account_id
+        table.boolean :is_default
+        table.index %i[account_id], unique: true, name: index_name, where: 'is_default = true'
+      end
+    end
+
+    let(:klass) { define_class }
+
+    specify do
+      expect(checker.report).to be_nil
+    end
+  end
+end

spec/checkers/unique_index_checker/sqlite_spec.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+RSpec.describe DatabaseConsistency::Checkers::UniqueIndexChecker, :sqlite do
+  subject(:checker) { described_class.new(model, index) }
+
+  let(:model) { klass }
+  let(:index) { ActiveRecord::Base.connection.indexes(klass.table_name).first }
+
+  let(:index_name) { 'index_name' }
+
+  context 'when unique partial index exists' do
+    before do
+      define_database_with_entity do |table|
+        table.integer :account_id
+        table.boolean :is_default
+        table.index %i[account_id], unique: true, name: index_name, where: 'is_default = 1'
+      end
+    end
+
+    let(:klass) { define_class }
+
+    specify do
+      expect(checker.report).to be_nil
+    end
+  end
+end