code: add support for failpoint.Inject("failpoint-name", nil) and Return marker function

[lonng]

Signed-off-by: Lonng chris@lonng.org

What problem does this PR solve?

• Support nil closure

  If we want a failpoint just sleep a duration like failpoint.Enable("failpoint-name", "sleep(500)), we must use a function without any statements and that will cause generated code line inconsistent.

  In following case:

  failpoint.Inject("failpoint-name", func(){})

  Will generate:

  if ok, _ := failpoint.Eval(_curpkg_("failpoint-name")); ok {
  }

• Add Return marker function

  func foo() (int, string) {
      // Some logic
      failpoint.Inject("failpoint-name", func(val failpoint.Value) (int, string) {
          // return early
          if val.(int) % 10 == 0 {
              return val.(int), "string from failpoint"
          }
          // We must write a return statement here to make the program legal
          return 0, "I do not want return anything here"
      })
      // Other logics
  }

  If we need an early return in failpoint with some conditions like above case. We will get unexpected result because there is always early return if failpoint is active. So we need a Return marker function.

  func foo() (int, string) {
      // Some logic
      failpoint.Inject("failpoint-name", func(val failpoint.Value) {
          // return early
          if val.(int) % 10 == 0 {
              failpoint.Return(val.(int), "string from failpoint")
          }
      })
      // Other logics
  }

What is changed and how it works?

Add support for nil closure, which will generate a failpoint.Eval(...) call instead of an IF statement.

Check List

Tests

• Unit test
• Integration test

Side effects

N/A

Related changes

N/A

[codecov[bot]]

Codecov Report

Merging #19 into master will increase coverage by 0.124%. The diff coverage is 100%.

@@               Coverage Diff               @@
##             master        #19       +/-   ##
===============================================
+ Coverage   78.5133%   78.6374%   +0.124%     
===============================================
  Files             7          7               
  Lines           861        866        +5     
===============================================
+ Hits            676        681        +5     
  Misses          109        109               
  Partials         76         76