EclEmma，Java8和Lambda

本文介绍了EclEmma，Java8和Lambda - 没有关于lambda表达式的报道的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我在Eclipse Luna下有一个Java项目，使用EclEmma 2.3.1.201405111647（最新版），它使用Jacoco 0.7.1，它支持Java 8，如更改日志：

版本2.3.1（2014/05） / 11）

修复了Eclipse 4.4（GitHub＃83）中新ASM包的ASM 5.0.1依赖冲突。升级到JaCoCo 0.7.1以获得完整的Java 8支持。

我现在有以下toString：

@Override public String toString（）{ // [ BLOCK0] if（0 == value）{返回0B; } // [BLOCK1] final MutableLong val = new MutableLong（value） ; final StringBuilder sb = new StringBuilder（）; // [BLOCK2] Arrays.asList（TERA_BYTES，GIGA_BYTES，MEGA_BYTES，KILO_BYTES，BYTES）.forEach（unit - > { // [BLOCK3] long divider = unit.toBytes（1）; long n = val.longValue（）/ divider; if（0！= n）{ sb.append（n）.append（unit.getUnitCharacter（））; val.subtract（n * divider）; } }）; // [BLOCK4] 返回sb.toString（）; }

我不会进行Junit测试，因为我知道它是100％覆盖。我可以通过将lamdba表达式移动到 appendToString 方法来证明这一点，并使用重新设置 forEach -each for（V值：Iterable< V>）。

结果是，当我做报道为Junit测试，如下：

• BLOCK0全为绿色
• BLOCK1全部为绿色
• BLOCK2为绿色，最高为 forEach（单位 - > {
• BLOCK3是白色的（好像被忽略了一行）
• BLOCK4全为绿色。

<有人能解释一下为什么Jacoco无法检测到lambda中的覆盖范围吗？

解决方案

将Lambda表达式体编译成合成方法，但据我所知，合成方法无条件过滤掉了代码覆盖率分析。

通过查看 JaCoCo的变更历史我看到了

快照构建0.7.2.201408210455（2014/08/21）

修正错误

不要忽略合成的lambda方法来获取Java 8 lambda表达式的代码覆盖率（GitHub＃232）。

<这似乎解决了你的问题。由于您使用的是使用JaCoCo版本 0.7.1 的EclEmma 2.3.1 ，您只需要更新。

I have a Java project under Eclipse Luna, with EclEmma 2.3.1.201405111647 (latest), which use Jacoco 0.7.1, which have support for Java 8 as stated in their changelog:

"Version 2.3.1 (2014/05/11)

Fixed ASM 5.0.1 dependency conflicts with new ASM bundles in Eclipse 4.4 (GitHub #83). Upgrade to JaCoCo 0.7.1 for full Java 8 support.

I now have the following toString:

@Override public String toString() { // [BLOCK0] if (0 == value) { return "0B"; } // [BLOCK1] final MutableLong val = new MutableLong(value); final StringBuilder sb = new StringBuilder(); // [BLOCK2] Arrays.asList(TERA_BYTES, GIGA_BYTES, MEGA_BYTES, KILO_BYTES, BYTES).forEach(unit -> { // [BLOCK3] long divider = unit.toBytes(1); long n = val.longValue() / divider; if (0 != n) { sb.append(n).append(unit.getUnitCharacter()); val.subtract(n * divider); } }); // [BLOCK4] return sb.toString(); }

I won't put the Junit test, because I know it goes 100% coverage. I can prove it by moving the lamdba expression into a appendToString method, and remplace the forEach with a for-each for (V value : Iterable<V>).

The result is, when I do "Coverage as Junit Test", the following:

• BLOCK0 is all green
• BLOCK1 is all green
• BLOCK2 is green, up to the forEach(unit -> {
• BLOCK3 is white (as if it were ignored lines)
• BLOCK4 is all green.

Can someone explain me why Jacoco can't detect coverage in lambda ?

解决方案

Lambda expression bodies are compiled into synthetic methods, but as far as I read, synthetic methods are unconditionally filtered out in the code coverage analysis.

By looking at the Change History of JaCoCo I see

Snapshot Build 0.7.2.201408210455 (2014/08/21)

Fixed Bugs

Do not ignore synthetic lambda methods to get code coverage for Java 8 lambda expressions (GitHub #232).

which seems to address your issue. Since you are using EclEmma 2.3.1 which is using JaCoCo version 0.7.1 you just need an update.