fixes #951

remix-tests/src/compiler.ts

@@ -153,6 +153,7 @@ export function compileContractSources(sources: SrcIfc, versionUrl: any, usingWo
     const accounts: string[] = opts.accounts || []
     // Iterate over sources keys. Inject test libraries. Inject test library import statements.
     if (!('remix_tests.sol' in sources) && !('tests.sol' in sources)) {
+        sources['tests.sol'] = { content: require('../sol/tests.sol.js') }
         sources['remix_tests.sol'] = { content: require('../sol/tests.sol.js') }
         sources['remix_accounts.sol'] = { content: writeTestAccountsContract(accounts) }
     }