Basic implementation of UnreachableCode rule

spec/ameba/ast/flow_expression_spec.cr

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+require "../../spec_helper"
+
+module Ameba::AST
+  describe FlowExpression do
+    describe "#initialize" do
+      it "creates a new flow expression" do
+        node = as_node("return 22")
+        parent_node = as_node("def foo; return 22; end")
+        flow_expression = FlowExpression.new node, parent_node
+        flow_expression.node.should_not be_nil
+        flow_expression.parent_node.should_not be_nil
+      end
+
+      describe "#delegation" do
+        it "delegates to_s to @node" do
+          node = as_node("return 22")
+          parent_node = as_node("def foo; return 22; end")
+          flow_expression = FlowExpression.new node, parent_node
+          flow_expression.to_s.should eq node.to_s
+        end
+
+        it "delegates location to @node" do
+          node = as_node %(break if true)
+          parent_node = as_node("def foo; return 22 if true; end")
+          flow_expression = FlowExpression.new node, parent_node
+          flow_expression.location.should eq node.location
+        end
+      end
+
+      describe "#find_unreachable_node" do
+        it "returns first unreachable node" do
+          nodes = as_nodes %(
+            def foobar
+              return
+              a = 1
+              a + 1
+            end
+          )
+          node = nodes.control_expression_nodes.first
+          assign_node = nodes.assign_nodes.first
+          def_node = nodes.def_nodes.first
+          flow_expression = FlowExpression.new node, def_node
+          flow_expression.find_unreachable_node.should eq assign_node
+        end
+
+        it "returns nil if there is no unreachable node" do
+          nodes = as_nodes %(
+            def foobar
+              a = 1
+              return a
+            end
+          )
+          node = nodes.control_expression_nodes.first
+          def_node = nodes.def_nodes.first
+          flow_expression = FlowExpression.new node, def_node
+          flow_expression.find_unreachable_node.should eq nil
+        end
+      end
+    end
+  end
+end

spec/ameba/ast/visitors/flow_expression_visitor_spec.cr

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+require "../../../spec_helper"
+
+module Ameba::AST
+  source = Source.new ""
+
+  describe FlowExpressionVisitor do
+    it "creates an expression for return" do
+      rule = FlowExpressionRule.new
+      FlowExpressionVisitor.new rule, Source.new %(
+        def foo
+          return :bar
+        end
+      )
+      rule.expressions.size.should eq 1
+    end
+
+    it "can create multiple expressions" do
+      rule = FlowExpressionRule.new
+      FlowExpressionVisitor.new rule, Source.new %(
+        def foo
+          if bar
+            return :baz
+          else
+            return :foobar
+          end
+        end
+      )
+      rule.expressions.size.should eq 2
+    end
+
+    it "properly creates nested flow expressions" do
+      rule = FlowExpressionRule.new
+      FlowExpressionVisitor.new rule, Source.new %(
+        def foo
+          return(
+            loop do
+              break if a > 1
+              return a
+            end
+          )
+        end
+      )
+      rule.expressions.size.should eq 3
+    end
+
+    it "creates an expression for break" do
+      rule = FlowExpressionRule.new
+      FlowExpressionVisitor.new rule, Source.new %(
+        while true
+          break
+        end
+      )
+      rule.expressions.size.should eq 1
+    end
+
+    it "creates an expression for next" do
+      rule = FlowExpressionRule.new
+      FlowExpressionVisitor.new rule, Source.new %(
+        while true
+          next if something
+        end
+      )
+      rule.expressions.size.should eq 1
+    end
+  end
+end