add equal operator

app/models/logic/eq.rb

@@ -0,0 +1,18 @@
+class Logic::Eq < Logic::BinaryOperator
+  def operation = :==
+
+  def errors(stable_ids = [])
+    errors = []
+
+    if !Logic.compatible_type?(@left, @right)
+      errors += ["les types sont incompatibles : #{self}"]
+    end
+
+    errors + @left.errors(stable_ids) + @right.errors(stable_ids)
+  end
+
+  def ==(other)
+    self.class == other.class &&
+      [@left, @right].permutation.any? { |p| p == [other.left, other.right] }
+  end
+end

spec/models/logic/eq_spec.rb

@@ -0,0 +1,17 @@
+describe Logic::Eq do
+  include Logic
+
+  describe '#compute' do
+    it { expect(ds_eq(constant(1), constant(1)).compute).to be(true) }
+    it { expect(ds_eq(constant(1), constant(2)).compute).to be(false) }
+  end
+
+  describe '#errors' do
+    it { expect(ds_eq(constant(true), constant(true)).errors).to be_empty }
+    it { expect(ds_eq(constant(true), constant(1)).errors).to eq(["les types sont incompatibles : (true == 1)"]) }
+  end
+
+  describe '#==' do
+    it { expect(ds_eq(constant(true), constant(false))).to eq(ds_eq(constant(false), constant(true))) }
+  end
+end