https://github.com/powermock/powermock/wiki/Code-coverage-with-JaCoCo
A example of JaCoCo-Offline-Instrumentation for gradle project.
$ ./gradlew clean build
$ ls build/classes/java/main/com/example/api/Api.class # on-the-fly
$ ls build/classes-instrumented/com/example/api/Api.class # offlineYou can't read .class file directly. Use IntelliJ IDEA or Eclipse.
Or, look at the example I provide. (/build/classes, /build/classes-instrumented)
Or, use javap. Of course, I'll provide an example.(/build/classes, /build/classes-instrumented)
// Api.class
package com.example.api;
public class Api {
private String greetingMsg = "Hello ";
private String name;
public Api(String name) {
this.name = name;
}
public int sum(int x, int y) {
return x + y;
}
public String getName() {
return this.name;
}
public String greeting() {
return this.greetingMsg + this.name;
}
}On-the-fly instrumentation doesn't manipulate the class file itself. Manipulate bytecode at runtime.
// Api.class
package com.example.api;
public class Api {
private String greetingMsg;
private String name;
public Api(String name) {
boolean[] var2 = $jacocoInit();
super();
this.greetingMsg = "Hello ";
this.name = name;
var2[0] = true;
}
public int sum(int x, int y) {
boolean[] var3 = $jacocoInit();
int var10000 = x + y;
var3[1] = true;
return var10000;
}
public String getName() {
boolean[] var1 = $jacocoInit();
var1[2] = true;
return this.name;
}
public String greeting() {
boolean[] var1 = $jacocoInit();
String var10000 = this.greetingMsg + this.name;
var1[3] = true;
return var10000;
}
}Offline instrumentation manipulates class files in advance.
$ javap -c Api.classpublic class com.example.api.Api {
public com.example.api.Api(java.lang.String);
Code:
0: aload_0
1: invokespecial #1 // Method java/lang/Object."<init>":()V
4: aload_0
5: ldc #2 // String Hello
7: putfield #3 // Field greetingMsg:Ljava/lang/String;
10: aload_0
11: aload_1
12: putfield #4 // Field name:Ljava/lang/String;
15: return
public int sum(int, int);
Code:
0: iload_1
1: iload_2
2: iadd
3: ireturn
public java.lang.String getName();
Code:
0: aload_0
1: getfield #4 // Field name:Ljava/lang/String;
4: areturn
public java.lang.String greeting();
Code:
0: new #5 // class java/lang/StringBuilder
3: dup
4: invokespecial #6 // Method java/lang/StringBuilder."<init>":()V
7: aload_0
8: getfield #3 // Field greetingMsg:Ljava/lang/String;
11: invokevirtual #7 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
14: aload_0
15: getfield #4 // Field name:Ljava/lang/String;
18: invokevirtual #7 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
21: invokevirtual #8 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
24: areturn
}$ javap -c Api.classpublic class com.example.api.Api {
public com.example.api.Api(java.lang.String);
Code:
0: invokestatic #47 // Method $jacocoInit:()[Z
3: astore_2
4: aload_0
5: invokespecial #1 // Method java/lang/Object."<init>":()V
8: aload_0
9: ldc #2 // String Hello
11: putfield #3 // Field greetingMsg:Ljava/lang/String;
14: aload_0
15: aload_1
16: putfield #4 // Field name:Ljava/lang/String;
19: aload_2
20: iconst_0
21: iconst_1
22: bastore
23: return
public int sum(int, int);
Code:
0: invokestatic #47 // Method $jacocoInit:()[Z
3: astore_3
4: iload_1
5: iload_2
6: iadd
7: aload_3
8: iconst_1
9: iconst_1
10: bastore
11: ireturn
public java.lang.String getName();
Code:
0: invokestatic #47 // Method $jacocoInit:()[Z
3: astore_1
4: aload_0
5: getfield #4 // Field name:Ljava/lang/String;
8: aload_1
9: iconst_2
10: iconst_1
11: bastore
12: areturn
public java.lang.String greeting();
Code:
0: invokestatic #47 // Method $jacocoInit:()[Z
3: astore_1
4: new #5 // class java/lang/StringBuilder
7: dup
8: invokespecial #6 // Method java/lang/StringBuilder."<init>":()V
11: aload_0
12: getfield #3 // Field greetingMsg:Ljava/lang/String;
15: invokevirtual #7 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
18: aload_0
19: getfield #4 // Field name:Ljava/lang/String;
22: invokevirtual #7 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
25: invokevirtual #8 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
28: aload_1
29: iconst_3
30: iconst_1
31: bastore
32: areturn
}- Look at the byte code, you can see the words '$jacocoInit'