The "study" is by 'Aspiring Minds' - an Indian company that sells buggy web-based pre-interview filtering tests as a service. It is in Aspiring Minds interest to portray Indian graduates as incompetent to make Indian employers buy their pre-interview filtering services.
Aspiring Minds tested engineering students from all fields (including chemical, mechanical and civil) to make up the misleading '90% of Indian graduates are stupid' headlines. It worked. The headlines went viral and people still quote their misleading study. The coding part of the test was to submit compile-able Java code through an HTML input without any syntax highlighting or formatting. Needless to say most chemical and civil engineering graduates will not be able to do that.
I was a CS student at an Indian engineering college. I was forced to take an Aspiring Minds test. The test was buggy and had no feedback. I probably failed. But today I'm a full-stack developer in Denmark. Most of my graduating class have good jobs and almost half of us work overseas.