Improvements on empty rescue and unused params in abstract method

spec/cra/workspace/completion_resolve_spec.cr

@@ -74,7 +74,7 @@ describe CRA::Workspace do
       contents = resolved.documentation.not_nil!.as_h
       contents["kind"].as_s.should eq("markdown")
       value = contents["value"].as_s
-      value.should contain("def Greeter#greet(name)")
+      value.should contain("def Greeter.greet(name)")
       value.should contain("Says hello.")
     end
   end

spec/cra/workspace/completion_spec.cr

@@ -448,4 +448,5 @@ describe CRA::Workspace do
       labels(items).should contain("foo/baz")
     end
   end
+
 end

spec/cra/workspace/diagnostic_spec.cr

@@ -141,6 +141,41 @@ describe CRA::Workspace do
     end
   end
 
+  it "warns on empty rescue" do
+    with_tmpdir do |dir|
+      code = <<-CR
+      begin
+        foo
+      rescue
+      end
+      CR
+      path = File.join(dir, "empty_rescue.cr")
+      File.write(path, code)
+      ws = workspace_for(dir)
+
+      params = ws.publish_diagnostics("file://#{path}")
+      params.diagnostics.any? { |d| d.source == "lint" && d.message.includes?("Empty rescue") }.should be_true
+    end
+  end
+
+  it "does not warn on non-empty rescue" do
+    with_tmpdir do |dir|
+      code = <<-CR
+      begin
+        foo
+      rescue
+        ch.send(nil)
+      end
+      CR
+      path = File.join(dir, "rescue_body.cr")
+      File.write(path, code)
+      ws = workspace_for(dir)
+
+      params = ws.publish_diagnostics("file://#{path}")
+      params.diagnostics.any? { |d| d.message.includes?("Empty rescue") }.should be_false
+    end
+  end
+
   it "hints trailing whitespace" do
     with_tmpdir do |dir|
       code = <<-CR
@@ -221,6 +256,23 @@ describe CRA::Workspace do
     end
   end
 
+  it "does not flag abstract def params as unused" do
+    with_tmpdir do |dir|
+      code = <<-CR
+      abstract class Foo
+        abstract def foo(a, _b, c)
+        abstract def bar(a : Int32) : String
+      end
+      CR
+      path = File.join(dir, "abstract_args.cr")
+      File.write(path, code)
+      ws = workspace_for(dir)
+
+      params = ws.publish_diagnostics("file://#{path}")
+      params.diagnostics.any? { |d| d.source == "lint" && d.message.includes?("Unused argument") }.should be_false
+    end
+  end
+
   it "hints unused block args" do
     with_tmpdir do |dir|
       code = <<-CR