Merge pull request #577 from crystal-ameba/tweak-lint-literal-in-cond…

…ition-rule

Tweak `Lint/LiteralInCondition` rule

spec/ameba/rule/lint/literal_in_condition_spec.cr

@@ -26,7 +26,23 @@ module Ameba::Rule::Lint
       subject.catch(s).should be_valid
     end
 
-    it "fails if there is a predicate in if conditional" do
+    it "fails if there is a predicate with non-literals" do
+      s = Source.new %(
+        :ok if     [foo, bar]
+        :ok unless [foo, bar]
+
+        while [foo, bar]
+          :ok
+        end
+
+        until [foo, bar]
+          :ok
+        end
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "fails if there is a predicate in `if` conditional" do
       s = Source.new %(
         if "string"
           :ok
@@ -35,7 +51,7 @@ module Ameba::Rule::Lint
       subject.catch(s).should_not be_valid
     end
 
-    it "fails if there is a predicate in unless conditional" do
+    it "fails if there is a predicate in `unless` conditional" do
       s = Source.new %(
         unless true
           :ok
@@ -44,6 +60,42 @@ module Ameba::Rule::Lint
       subject.catch(s).should_not be_valid
     end
 
+    it "fails if there is a predicate in `while` conditional" do
+      s = Source.new %(
+        while 1
+          :ok
+        end
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "fails if there is a `false` predicate in `while` conditional" do
+      s = Source.new %(
+        while false
+          :ok
+        end
+      )
+      subject.catch(s).should_not be_valid
+    end
+
+    it "passes if there is a `true` predicate in `while` conditional" do
+      s = Source.new %(
+        while true
+          :ok
+        end
+      )
+      subject.catch(s).should be_valid
+    end
+
+    it "fails if there is a predicate in `until` conditional" do
+      s = Source.new %(
+        until true
+          :foo
+        end
+      )
+      subject.catch(s).should_not be_valid
+    end
+
     describe "range" do
       it "reports range with literals" do
         s = Source.new %(

src/ameba/rule/lint/literal_in_condition.cr

@@ -3,7 +3,7 @@ module Ameba::Rule::Lint
   # in place of a variable or predicate function.
   #
   # This is because a conditional construct with a literal predicate will
-  # always result in the same behaviour at run time, meaning it can be
+  # always result in the same behavior at run time, meaning it can be
   # replaced with either the body of the construct, or deleted entirely.
   #
   # This is considered invalid:
@@ -31,10 +31,23 @@ module Ameba::Rule::Lint
 
     MSG = "Literal value found in conditional"
 
-    def test(source, node : Crystal::If | Crystal::Unless | Crystal::Case)
+    def test(source, node : Crystal::If | Crystal::Unless | Crystal::Until)
+      issue_for node.cond, MSG if literal?(node.cond)
+    end
+
+    def test(source, node : Crystal::Case)
       return unless cond = node.cond
+      return unless static_literal?(cond)
+
+      issue_for cond, MSG
+    end
+
+    def test(source, node : Crystal::While)
+      return unless literal?(cond = node.cond)
+      # allow `while true`
+      return if cond.is_a?(Crystal::BoolLiteral) && cond.value
 
-      issue_for cond, MSG if static_literal?(cond)
+      issue_for cond, MSG
     end
   end
 end