I am trying to write a script in Go but I get this error:
bad interpreter: Permission denied
My super simple script is as follow:
#!/usr/local/Cellar/go/1.0.2/bin
fmt.Println("Hello World")
I don´t know if this is possible but I would really like to write scripts in Go since I like the language a lot.
Go isn't a scripting language. Like in C you have to compile your source code to make an executable.
From the "Getting Started" :
Create a file named hello.go and put the following program in it:
package main
import "fmt"
func main() {
fmt.Printf("hello, world\n")
}
Then run it with the go tool:
$ go run hello.go
hello, world
In the spirit of Python, there are attempts to make Go scripts kinda possible. Here's for example what you can do with gorun :
#!/usr/bin/gorun
package main
func main() {
println("Hello world!")
}
But that's not really the logic of Go and that's not nearly as simple as what you typed in your question.
Related
I want to lock the user-facing command line API of my golang program by writing few anti-regression tests that would focus on testing my binary as a whole. What testing "binary as a whole" means is that go-test should:
be able to feed STDIN to my binary
be able to check that my binary produces correct STDOUT
be able to ensure that error cases are handled properly by binary
However, it is not obvious to me what is the best practice to do that in go? If there is a good go test example, could you point me to it?
P.S. in the past I have been using autotools. And I am looking for something similar to AT_CHECK, for example:
AT_CHECK([echo "XXX" | my_binary -e arg1 -f arg2], [1], [],
[-f and -e can't be used together])
Just make your main() single line:
import "myapp"
func main() {
myapp.Start()
}
And test myapp package properly.
EDIT:
For example, popular etcd conf server uses this technique: https://github.com/coreos/etcd/blob/master/main.go
I think you're trying too hard: I just tried the following
func TestMainProgram(t *testing.T) {
os.Args = []string{"sherlock",
"--debug",
"--add", "zero",
"--ruleset", "../scripts/ceph-log-filters/ceph.rules",
"../scripts/ceph-log-filters/ceph.log"}
main()
}
and it worked fine. I can make a normal tabular test or a goConvey BDD from it pretty easily...
If you really want to do such type of testing in Go, you can use Go os/exec package https://golang.org/pkg/os/exec/ to execute your binary and test it as a whole - for example, executing go run main.go command. Essentially it would be an equivalent of a shell script done in Go. You can use StdinPipe https://golang.org/pkg/os/exec/#Cmd.StdinPipe and StdouPipe/StderrPipe (https://golang.org/pkg/os/exec/#Cmd.StdoutPipe and https://golang.org/pkg/os/exec/#Cmd.StderrPipe) to feed the desired input and verify output. The examples on the package documentation page https://golang.org/pkg/os/exec/ should give you a good starting point.
However, the testing of compiled programs goes beyond the unit testing so it is worth to consider other tools (not necessarily Go-based) that more typically used for functional / acceptance testing such as Cucumber http://cucumber.io.
I tried to import System.Directory in my Frege program (In Eclipse) in order to use functions as getDirectoryContent, etc., and it writes me this error :
Could not import module frege.system.Directory (java.lang.ClassNotFoundException: frege.system.Directory)
What do I have to do ?
It is because the module frege.system.Directory doesn't exist in Frege. A good way to find out about a module is to use Hoogle for Frege at this URL: http://hoogle.haskell.org:8081. If we search for that module there, we can see that it doesn't list any module as opposed to, say, if you search for frege.data.List, we would see the module in the result.
Now for the functions you need like getDirectoryContent, if you look at the search result for frege.system.Directory, the first result is about processes and the third and fourth results are about jars and zip files. If you click on the second result, it would open the module frege.java.IO and you can see some relevant functions that might be useful for you (list for example). However the Haskell module you are trying to find is not yet ported to Frege but it should, of course, be possible to port that module backed by native Java implementations.
Update for OP's comment
Here is a simple snippet to return the files under a given directory:
ls :: String -> IO [String]
ls dir = do
contents <- File.new dir >>= _.list
maybe (return []) (JArray.fold (flip (:)) []) contents
Regarding createTempFile, the following works for me:
frege> File.createTempFile "test.txt"
String -> STMutable RealWorld File
Testable Go examples look awesome.
func ExampleReverse() {
fmt.Println(stringutil.Reverse("hello"))
// Output: olleh
}
The above, for example, is equivalent to a unit test that asserts:
stringutil.Reverse("hello") == "olleh"
According to the golang blog, we can write examples that don't have an output comment, but then the go test and go test -run ExampleReverse commands only compile the example and don't run it:
If we remove the output comment entirely then the example function is compiled but not executed. Examples without output comments are useful for demonstrating code that cannot run as unit tests, such as that which accesses the network, while guaranteeing the example at least compiles.
The output of such examples, although not testable, could still be useful for the user to produce and read. And the examples themselves - useful to run on their computer.
So is there a way or a tool that can run example functions in *_test.go files from the terminal?
You can call the Example* functions from a regular Test* function.
func ExampleOutput() {
fmt.Println("HEELLO")
}
func TestExampleOutput(t *testing.T) {
if !testing.Verbose() {
return
}
ExampleOutput()
}
This body of this example would show up under Output in the docs, and if you don't want the output every time, it's limited to only calling it with the -v flag.
Specifically, to run only the example you're interested in you can either:
go test path/to/pkg -run TestExampleOutput -v
Or to compile once and run multiple times:
go test path/to/pkg -c
./pkg.test -test.run TestExampleOutput -test.v
I am a little confused about how to structure a go web app and its tests. I have read the How to Write Go Code but still don't get it. For example, I have a go project called "beacon" with a beacon.go file at the root. Adding a trivial beacon_test.go file (copied verbatim from http://golang.org/pkg/net/http/httptest/#example_Server) causes this error:
$ go test
# github.com/jelder/beacon
./beacon_test.go:11: main redeclared in this block
previous declaration at ./beacon.go:216
FAIL github.com/jelder/beacon [build failed]
Sure enough, line 11 is func main(). If I instead change the package main line in my beacon_test.go to package hello, I get this error instead:
can't load package: package github.com/jelder/beacon: found packages main (beacon.go) and hello (beacon_test.go) in /Users/jacob/src/github.com/jelder/beacon
beacon_test.go has also a function called main() rename it to TestFirst (or any other name you like as long as it starts with Test, note the uppercase T is important). There is no need for that. Just run go test . from inside the package you are working on (the one containing the *.go files). Post the full files if you need more help.
I am currently looking at using Scala scripts to control the life-cycle of a MySQL database instead of using MS-DOS scripts (I am on Windows XP).
I want to have a configuration script which only holds configuration information, and 1 or more management scripts which use the configuration information to perform various operations such as start, stop, show status, etc .....
Is it possible to write a Scala script which includes/imports/references another Scala script?
I had a look at the -i option of the scala interpreter, but this launches an interactive session which is not what I want.
According to Scala man, script pre-loading only works for interactive mode.
As a workaround, you can exit the interactive mode after running the script. Here's the code of child.bat (script that includes another generic one):
::#!
#echo off
call scala -i genetic.bat %0
goto :eof
::!#
def childFunc="child"
println(geneticFunc)
println(childFunc)
exit;
genericFunc is defined at genetic.bat
The output of child.bat:
>child.bat
Loading genetic.bat...
...
geneticFunc: java.lang.String
Loading child.bat...
...
childFunc: java.lang.String
generic
child
I'd use Process and call the other Scala script just like any other command.
One option would be to have a script which concatenates two files together and then launches it, something like:
#echo off
type config.scala > temp.scala
type code.scala >> temp.scala
scala temp.scala
del temp.scala
or similar. Then you keep the two seperate as you wished.