Basic implementation of UnreachableCode rule

spec/ameba/rule/lint/unreachable_code_spec.cr

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+require "../../../spec_helper"
+
+module Ameba::Rule::Lint
+  subject = UnreachableCode.new
+
+  describe UnreachableCode do
+    context "return" do
+      it "reports if there is unreachable code after return" do
+        s = Source.new %(
+          def foo
+            a = 1
+            return false
+            b = 2
+          end
+        )
+        subject.catch(s).should_not be_valid
+
+        issue = s.issues.first
+        issue.location.to_s.should eq ":4:3"
+      end
+
+      it "doesn't report if there is return in if" do
+        s = Source.new %(
+          def foo
+            a = 1
+            return false if bar
+            b = 2
+          end
+        )
+        subject.catch(s).should be_valid
+      end
+
+      it "doesn't report if there are returns in if-then-else" do
+        s = Source.new %(
+          if a > 0
+            return :positivie
+          else
+            return :negative
+          end
+        )
+        subject.catch(s).should be_valid
+      end
+    end
+
+    context "break" do
+      it "reports if there is unreachable code after break" do
+        s = Source.new %(
+          def foo
+            loop do
+              break
+              a = 1
+            end
+          end
+        )
+        subject.catch(s).should_not be_valid
+
+        issue = s.issues.first
+        issue.location.to_s.should eq ":4:5"
+      end
+
+      it "doesn't report if break is in a condition" do
+        s = Source.new %(
+          a = -100
+          while true
+            break if a > 0
+            a += 1
+          end
+        )
+        subject.catch(s).should be_valid
+      end
+    end
+
+    context "next" do
+      it "reports if there is unreachable code after next" do
+        s = Source.new %(
+          a = 1
+          while a < 5
+            next
+            puts a
+          end
+        )
+        subject.catch(s).should_not be_valid
+
+        issue = s.issues.first
+        issue.location.to_s.should eq ":4:3"
+      end
+
+      it "doesn't report if next is in a condition" do
+        s = Source.new %(
+          a = 1
+          while a < 5
+            if a == 3
+              next
+            end
+            puts a
+          end
+        )
+        subject.catch(s).should be_valid
+      end
+    end
+  end
+end