Switch Test's mochaRunner to be a Promise

... so that it can be awaited rather than statefully undefined

Author: gnidan

packages/core/lib/debug/mocha.js

@@ -18,7 +18,7 @@ class CLIDebugHook {
     // turn off timeouts for the current runnable
     // HACK we don't turn it back on because it doesn't work...
     // tests that take a long time _after_ debug break just won't timeout
-    this.disableTimeout();
+    await this.disableTimeout();
 
     const { txHash, result, method } = await this.invoke(operation);
     debug("txHash: %o", txHash);
@@ -38,8 +38,8 @@ class CLIDebugHook {
 
   async start() {}
 
-  disableTimeout() {
-    this.runner.currentRunnable.timeout(0);
+  async disableTimeout() {
+    (await this.runner).currentRunnable.timeout(0);
   }
 
   async invoke(operation) {

packages/test/src/Test.ts

@@ -90,6 +90,17 @@ export const Test = {
 
     const mocha = this.createMocha(config);
 
+    // set up a promise on this instance to resolve to
+    // Mocha's "runner" returned by `mocha.run(...)`.
+    //
+    // do this upfront so that the promise is available
+    // immediately, even though mocha.run happens at the very
+    // end of this setup.
+    let setMochaRunner: (mochaRunner: any) => void;
+    this.mochaRunner = new Promise(resolve => {
+      setMochaRunner = resolve;
+    });
+
     const jsTests = config.test_files.filter((file: string) => {
       return path.extname(file) !== ".sol";
     });
@@ -177,10 +188,14 @@ export const Test = {
     });
 
     return new Promise(resolve => {
-      this.mochaRunner = mocha.run((failures: number) => {
+      const mochaRunner = mocha.run((failures: number) => {
         config.logger.warn = warn;
         resolve(failures);
       });
+
+      // finish setting up the mocha runner so that the
+      // previously-made promise resolves.
+      setMochaRunner(mochaRunner);
     });
   },