Properly report literals (#96)

spec/ameba/rule/lint/literal_in_condition_spec.cr

@@ -44,7 +44,26 @@ module Ameba::Rule::Lint
       subject.catch(s).should_not be_valid
     end
 
-    it "fails if there is a predicate in case conditional" do
+    describe "range" do
+      it "reports range with literals" do
+        s = Source.new %(
+          case 1..2
+          end
+        )
+        subject.catch(s).should_not be_valid
+      end
+
+      it "doesn't report range with non-literals" do
+        s = Source.new %(
+          case (1..a)
+          end
+        )
+        subject.catch(s).should be_valid
+      end
+    end
+
+    describe "array" do
+      it "reports array with literals" do
         s = Source.new %(
           case [1, 2, 3]
           when :array
@@ -56,6 +75,93 @@ module Ameba::Rule::Lint
         subject.catch(s).should_not be_valid
       end
 
+      it "doesn't report array with non-literals" do
+        s = Source.new %(
+          a, b = 1, 2
+          case [1, 2, a]
+          when :array
+            :ok
+          when :not_array
+            :also_ok
+          end
+        )
+        subject.catch(s).should be_valid
+      end
+    end
+
+    describe "hash" do
+      it "reports hash with literals" do
+        s = Source.new %(
+          case { "name" => 1, 33 => 'b' }
+          when :hash
+            :ok
+          end
+        )
+        subject.catch(s).should_not be_valid
+      end
+
+      it "doesn't report hash with non-literals in keys" do
+        s = Source.new %(
+          case { a => 1, 33 => 'b' }
+          when :hash
+            :ok
+          end
+        )
+        subject.catch(s).should be_valid
+      end
+
+      it "doesn't report hash with non-literals in values" do
+        s = Source.new %(
+          case { "name" => a, 33 => 'b' }
+          when :hash
+            :ok
+          end
+        )
+        subject.catch(s).should be_valid
+      end
+    end
+
+    describe "tuple" do
+      it "reports tuple with literals" do
+        s = Source.new %(
+          case {1, false}
+          when {1, _}
+            :ok
+          end
+        )
+        subject.catch(s).should_not be_valid
+      end
+
+      it "doesn't report tuple with non-literals" do
+        s = Source.new %(
+          a, b = 1, 2
+          case {1, b}
+          when {1, 2}
+            :ok
+          end
+        )
+        subject.catch(s).should be_valid
+      end
+    end
+
+    describe "named tuple" do
+      it "reports named tuple with literals" do
+        s = Source.new %(
+          case { name: 1, foo: :bar}
+          end
+        )
+        subject.catch(s).should_not be_valid
+      end
+
+      it "doesn't report named tuple with non-literals" do
+        s = Source.new %(
+          case { name: a, foo: :bar}
+          end
+        )
+        subject.catch(s).should be_valid
+      end
+    end
+
     it "reports rule, pos and message" do
       s = Source.new %(
         puts "hello" if true

src/ameba/ast/util.cr

@@ -2,7 +2,29 @@
 module Ameba::AST::Util
   # Returns true if current `node` is a literal, false otherwise.
   def literal?(node)
-    node.try &.class.name.ends_with? "Literal"
+    case node
+    when Crystal::NilLiteral,
+         Crystal::BoolLiteral,
+         Crystal::NumberLiteral,
+         Crystal::CharLiteral,
+         Crystal::StringLiteral,
+         Crystal::SymbolLiteral,
+         Crystal::RegexLiteral,
+         Crystal::ProcLiteral,
+         Crystal::MacroLiteral
+      true
+    when Crystal::RangeLiteral
+      literal?(node.from) && literal?(node.to)
+    when Crystal::ArrayLiteral,
+         Crystal::TupleLiteral
+      node.elements.all? { |el| literal?(el) }
+    when Crystal::HashLiteral
+      node.entries.all? { |entry| literal?(entry.key) && literal?(entry.value) }
+    when Crystal::NamedTupleLiteral
+      node.entries.all? { |entry| literal?(entry.value) }
+    else
+      false
+    end
   end
 
   # Returns true if current `node` is a string literal, false otherwise.