Respect bug for Ruby v3.0 in tests

spec/lib/im-lost_spec.rb

@@ -9,6 +9,9 @@ def initialize
     @bar = 22
   end
 
+  def baz = 'baz'
+  def nix = 'nix'
+
   def add(arg0, arg1) = arg0 + arg1
   def add_kw(arg0:, arg1:) = arg0 + arg1
   def add_block(arg, &block) = arg + block[]
@@ -38,11 +41,22 @@ def fwd(...) = add(...)
 
     after { ImLost.untrace_all! }
 
-    it 'traces method calls' do
-      expect { sample.foo + sample.bar }.to write <<~OUTPUT
-        > TestSample#foo()
-        > TestSample#bar()
-      OUTPUT
+    if RUBY_VERSION.to_f <= 3.0
+      # there is a bug in Ruby 3.0 which does not allow to trace
+      # methods declared with attr_xxx
+      it 'traces method calls' do
+        expect { sample.baz + sample.nix }.to write <<~OUTPUT
+          > TestSample#baz()
+          > TestSample#nix()
+        OUTPUT
+      end
+    else
+      it 'traces method calls' do
+        expect { sample.foo + sample.bar }.to write <<~OUTPUT
+          > TestSample#foo()
+          > TestSample#bar()
+        OUTPUT
+      end
     end
 
     it 'includes arguments in call signatures' do
@@ -119,8 +133,8 @@ def fwd(...) = add(...)
     it 'can include caller locations' do
       ImLost.caller_locations = true
 
-      expect { sample.foo }.to write <<~OUTPUT
-        > TestSample#foo()
+      expect { sample.add(1, 1) }.to write <<~OUTPUT
+        > TestSample#add(1, 1)
           #{__FILE__}:#{__LINE__ - 2}
       OUTPUT
     end
@@ -136,13 +150,26 @@ def fwd(...) = add(...)
 
     after { ImLost.untrace_all! }
 
-    it 'traces method call results' do
-      expect { sample.foo + sample.bar }.to write <<~OUTPUT
-        < TestSample#foo()
-          = 20
-        < TestSample#bar()
-          = 22
-      OUTPUT
+    if RUBY_VERSION.to_f <= 3.0
+      # there is a bug in Ruby 3.0 which does not allow to trace
+      # methods declared with attr_xxx
+      it 'traces method call results' do
+        expect { sample.baz + sample.nix }.to write <<~OUTPUT
+          < TestSample#baz()
+            = "baz"
+          < TestSample#nix()
+            = "nix"
+        OUTPUT
+      end
+    else
+      it 'traces method call results' do
+        expect { sample.foo + sample.bar }.to write <<~OUTPUT
+          < TestSample#foo()
+            = 20
+          < TestSample#bar()
+            = 22
+        OUTPUT
+      end
     end
 
     it 'includes arguments in call signatures' do