test: improve coverage

packages/runtime-core/src/component.ts

@@ -690,6 +690,7 @@ const classifyRE = /(?:^|[-_])(\w)/g
 const classify = (str: string): string =>
   str.replace(classifyRE, c => c.toUpperCase()).replace(/[-_]/g, '')
 
+/* istanbul ignore next */
 export function formatComponentName(
   instance: ComponentInternalInstance | null,
   Component: Component,

packages/runtime-core/src/warning.ts

@@ -57,6 +57,7 @@ export function warn(msg: string, ...args: any[]) {
     )
   } else {
     const warnArgs = [`[Vue warn]: ${msg}`, ...args]
+    /* istanbul ignore if */
     if (
       trace.length &&
       // avoid spamming console during tests
@@ -99,6 +100,7 @@ function getComponentTrace(): ComponentTraceStack {
   return normalizedStack
 }
 
+/* istanbul ignore next */
 function formatTrace(trace: ComponentTraceStack): any[] {
   const logs: any[] = []
   trace.forEach((entry, i) => {
@@ -122,6 +124,7 @@ function formatTraceEntry({ vnode, recurseCount }: TraceEntry): any[] {
     : [open + close]
 }
 
+/* istanbul ignore next */
 function formatProps(props: Data): any[] {
   const res: any[] = []
   const keys = Object.keys(props)
@@ -136,6 +139,7 @@ function formatProps(props: Data): any[] {
 
 function formatProp(key: string, value: unknown): any[]
 function formatProp(key: string, value: unknown, raw: true): any
+/* istanbul ignore next */
 function formatProp(key: string, value: unknown, raw?: boolean): any {
   if (isString(value)) {
     value = JSON.stringify(value)