add more e2e tests

Signed-off-by: odubajDT <[email protected]>

Author: odubajDT

pkg/ottl/e2e/e2e_test.go

@@ -335,6 +335,12 @@ func Test_e2e_converters(t *testing.T) {
 				tCtx.GetLogRecord().Attributes().PutStr("SOMETHING", "myvalue")
 			},
 		},
+		{
+			statement: `set(attributes[ConvertCase(attributes[attributes["flags"]], "upper")], "myvalue")`,
+			want: func(tCtx ottllog.TransformContext) {
+				tCtx.GetLogRecord().Attributes().PutStr("SOMETHING", "myvalue")
+			},
+		},
 		{
 			statement: `set(attributes[attributes["flags"]], "something33")`,
 			want: func(tCtx ottllog.TransformContext) {