fix(web): remedy unit-test stability issues

Fixes: #11844

common/predictive-text/unit_tests/headless/worker-trie-integration.js

@@ -15,7 +15,7 @@ describe('LMLayer using the trie model', function () {
 
   beforeEach(function() {
     worker = Worker.constructInstance();
-    lmLayer = new LMLayer(capabilities(), worker);
+    lmLayer = new LMLayer(capabilities(), worker, true);
   });
 
   afterEach(function () {
@@ -82,7 +82,8 @@ describe('LMLayer using the trie model', function () {
         var suggestions = rawSuggestions.filter(function skimKeepSuggestions(s) {
           return s.tag !== 'keep'
         })
-        assert.isAtLeast(suggestions.length, 1)
+        assert.isAtLeast(rawSuggestions.length, 1);
+        assert.isAtLeast(suggestions.length, 1);
 
         // We SHOULD get 'naïve' suggested
         var topSuggestion = suggestions[0];

common/web/lm-worker/src/test/mocha/cases/worker-model-compositor.js

@@ -189,9 +189,19 @@ describe('ModelCompositor', function() {
 
         await Promise.all([firstPredict, secondPredict]);
 
-        const terminatedSuggestions = await firstPredict;
+        // We can't make many solid guarantees about the state at which the first predict()
+        // call was interrupted.
+        //
+        // Possible cases:
+        // - an early OS-level context switch can land between processing the root search node
+        //   and the first possible search result (even for a single char)
+        // - It's possible to interrupt after the first result (exact match) and before any
+        //   secondary corrections may be found
+        // - It's possible to interrupt "too late" if the correction search proceeds quickly,
+        //   returning a standard full set.
+        await firstPredict;
         const finalSuggestions = await secondPredict;
-        assert.isOk(terminatedSuggestions.find((entry) => entry.displayAs == 'a'));
+
         assert.isOk(finalSuggestions.find((entry) => entry.displayAs == 'applied'));
       });
     });