Fix coverage

.solcover.js

@@ -0,0 +1,28 @@
+module.exports = {
+    configureYulOptimizer: true,
+    solcOptimizerDetails: {
+        yul: true,
+        yulDetails: {
+            optimizerSteps:
+                'dhfoDgvlfnTUtnIf' +                // None of these can make stack problems worse
+                '[' +
+                    'xa[r]EscLM' +                  // Turn into SSA and simplify
+                    'cCTUtTOntnfDIl' +              // Perform structural simplification
+                    'Lcl' +                         // Simplify again
+                    'Vcl [j]' +                     // Reverse SSA
+
+                // should have good 'compilability' property here.
+
+                    'Tpel' +                        // Run functional expression inliner
+                    'xa[rl]' +                      // Prune a bit more in SSA
+                    'xa[r]cL' +                     // Turn into SSA again and simplify
+                    'gvf' +                         // Run full inliner
+                    'CTUca[r]LSsTFOtfDnca[r]Ilc' +  // SSA plus simplify
+                ']' +
+                'jml[jl] VcTOcl jml : fDnTOcm',     // Make source short and pretty
+        },
+    },
+    skipFiles: [
+        'mocks', 'tests', 'interfaces',
+    ],
+}