test: improve coverage

packages/compiler-core/src/codegen.ts

@@ -277,6 +277,7 @@ function genNode(node: CodegenNode, context: CodegenContext) {
       genArrayExpression(node, context)
       break
     default:
+      /* istanbul ignore next */
       __DEV__ &&
         assert(false, `unhandled codegen node type: ${(node as any).type}`)
   }
@@ -399,7 +400,7 @@ function genFor(node: ForNode, context: CodegenContext) {
   }
   if (keyAlias) {
     if (!valueAlias) {
-      push(`_`)
+      push(`__value`)
     }
     push(`, `)
     genExpression(keyAlias, context)
@@ -407,9 +408,9 @@ function genFor(node: ForNode, context: CodegenContext) {
   if (objectIndexAlias) {
     if (!keyAlias) {
       if (!valueAlias) {
-        push(`_, __`)
+        push(`__value, __key`)
       } else {
-        push(`__`)
+        push(`, __key`)
       }
     }
     push(`, `)
@@ -447,12 +448,9 @@ function genObjectExpression(node: ObjectExpression, context: CodegenContext) {
     // value
     genExpression(value, context)
     if (i < properties.length - 1) {
-      if (multilines) {
-        push(`,`)
-        newline()
-      } else {
-        push(`, `)
-      }
+      // will only reach this if it's multilines
+      push(`,`)
+      newline()
     }
   }
   multilines && deindent()

packages/compiler-core/src/parse.ts

@@ -199,6 +199,7 @@ function pushNode(
   node: ChildNode
 ): void {
   // ignore comments in production
+  /* istanbul ignore next */
   if (!__DEV__ && node.type === NodeTypes.COMMENT) {
     return
   }

packages/compiler-core/src/transform.ts

@@ -85,6 +85,7 @@ function createTransformContext(
     childIndex: 0,
     currentNode: null,
     replaceNode(node) {
+      /* istanbul ignore if */
       if (__DEV__ && !context.currentNode) {
         throw new Error(`node being replaced is already removed.`)
       }
@@ -97,6 +98,7 @@ function createTransformContext(
         : context.currentNode
           ? context.childIndex
           : -1
+      /* istanbul ignore if */
       if (__DEV__ && removalIndex < 0) {
         throw new Error(`node being removed is not a child of current parent`)
       }

packages/compiler-core/src/utils.ts

@@ -60,6 +60,7 @@ export function advancePositionWithMutation(
 }
 
 export function assert(condition: boolean, msg?: string) {
+  /* istanbul ignore if */
   if (!condition) {
     throw new Error(msg || `unexpected compiler condition`)
   }