Use different context instance for each noop span

lib/opentelemetry/context.lua

@@ -20,7 +20,7 @@ local baggage_context_key = "__opentelemetry_baggage__"
 -- @return              context
 --------------------------------------------------------------------------------
 function _M.new(entries, span)
-    return setmetatable({ sp = span or noop_span, entries = entries or {} }, mt)
+    return setmetatable({ sp = span or noop_span.new(), entries = entries or {} }, mt)
 end
 
 --------------------------------------------------------------------------------

lib/opentelemetry/trace/noop_span.lua

@@ -1,10 +1,18 @@
-local empty_span_context = require("opentelemetry.trace.span_context").new()
+local empty_span_context = require("opentelemetry.trace.span_context")
 
 local _M = {
 }
 
+local mt = {
+    __index = _M
+}
+
+function _M.new()
+    return setmetatable({ ctx = empty_span_context.new() }, mt)
+end
+
 function _M.context(self)
-    return empty_span_context
+    return self.ctx
 end
 
 function _M.is_recording()

spec/context_spec.lua

@@ -19,6 +19,18 @@ describe("current", function()
         otel_global.set_context_storage(ctx_storage)
         assert.are.equal(ctx_2, context.current())
     end)
+
+    it("instantiates different noop spans when no span provided", function()
+        local ctx_1 = context.new()
+        local ctx_2 = context.new()
+
+        -- accessing span context on different contexts gives different object back
+        assert.are_not.equal(ctx_1.sp:context(), ctx_2.sp:context())
+        assert.are_not.equal(ctx_1.sp:context().trace_state, ctx_2.sp:context().trace_state)
+
+        -- accessing span context on same context gives same object back
+        assert.are.equal(ctx_1.sp:context(), ctx_1.sp:context())
+    end)
 end)
 
 describe("with_span", function()