Add support for gomock (#235)

application/skeleton/main.go

@@ -1,3 +1,5 @@
+//go:generate sh tools/scripts/mockgen.sh
+
 package main
 
 import (

application/skeleton/test/example.go

@@ -0,0 +1,13 @@
+package test
+
+type Example interface {
+	HelloWorld() string
+}
+
+type test struct {
+	ex Example
+}
+
+func (t test) Run() string {
+	return t.ex.HelloWorld()
+}

application/skeleton/test/example_test.go

@@ -0,0 +1,17 @@
+package test
+
+import (
+	"github.com/golang/mock/gomock"
+	"testing"
+)
+
+func TestTest_Run(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	ex := NewMockExample(ctrl)
+	ex.EXPECT().HelloWorld().Times(1).Return("HelloWorld!")
+
+	tst := test{ex: ex}
+	if output := tst.Run(); output != "HelloWorld!" {
+		t.Errorf("expected Run() function to return 'HelloWorld!', got '%s'", output)
+	}
+}

application/skeleton/tools.go

@@ -0,0 +1,8 @@
+//go:build tools
+// +build tools
+
+package tools
+
+import (
+	_ "github.com/golang/mock/mockgen"
+)

application/skeleton/tools/scripts/mockgen.sh.twig

@@ -0,0 +1,23 @@
+#!/bin/sh
+
+{% apply spaceless %}
+{% for path in @('app.mockgen.paths') %}
+  {% if @('app.mockgen.mode') == "source" %}
+
+    {% set pathParts = path.source|split('/') %}
+    {% set package = path.package | default(pathParts[pathParts|length-2]) %}
+    {% set destination = path.destination | default(path.source|trim('.go', 'right') ~ '_mocks.go') %}
+
+    test {{ destination }} -nt {{ path.source }} || go run github.com/golang/mock/mockgen -source={{ path.source }} -package={{ package }} -destination={{ destination }}
+
+  {% elseif @('app.mockgen.mode') == "reflect" %}
+
+    {% set pathParts = path.import|split('/') %}
+    {% set package = path.package | default(pathParts|last) %}
+    {% set destination = path.destination | default(pathParts|slice(1)|join('/') ~ '/mocks.go') %}
+
+    go run github.com/golang/mock/mockgen -package={{ package }} -destination={{ destination }} {{ path.import }} {{ path.symbols }}
+
+  {% endif %}
+{% endfor %}
+{% endapply %}

docs/how-to-guides/use-gomock.md

@@ -0,0 +1,55 @@
+# How to use gomock
+
+[gomock] is a mocking library for GoLang. It works by generating the mocks for the interfaces you have defined in your 
+source code. The Go Harness comes with this library pre-installed and enabled. However, you would need to define the 
+source files for which you want to generate the mocks.
+
+## Defining mocks
+
+You can define the source paths for the mock generation in `workspace.yml`. By default, the harness comes with an example 
+test under `test` directory, and the mock path is defined for it too. Feel free to remove it and override the `app.mockgen`
+attribute as per your requirement.
+The `app.mockgen` attribute can contain following possible values:
+```yaml
+attributes:
+  app:
+    mockgen:
+        mode: source
+        paths:
+          - source: "./test/example.go"
+            package: "test"
+            destination: "./test/example_mocks.go"
+        mode: reflect
+        paths:
+          - import: "ci-go-sample/test"
+            symbols: "Example"
+            package: "test"
+            destination: "./test/example_mocks.go"
+```
+- `mode` defines the mockgen operation mode. There are two modes possible, `source` and `reflect`. For more information, 
+check [mockgen modes]. You can only use one of them.
+- Depending on the mode you have selected, you would need to provide the paths:
+  - `source` mode: in this mode, the only required attribute is `paths.source`, which contains the relative path of the 
+  source file which contains the interface(s) for which you want to generate the mock(s).  
+  - `reflect` mode: in this mode, you need to provide `paths.import` and `paths.symbols`. The `paths.import` contains the path
+  of the package from which you want to generate the mock(s), and `paths.symbols` contains a comma-separated list of 
+  interface names from that package for which the mocks would be generated.
+- The `paths.package` and `paths.destination` attributes are optional in both modes. If you don't pass them, they will be auto-inferred.
+
+## Commands
+
+### `ws install --step prepare`
+
+After modifying the `app.mockgen` attribute, you need to run this command. It will regenerate the `tools/scripts/mockgen.sh` script.
+
+### `ws go generate`
+
+Runs `go generate` command, which will internally execute `tools/scripts/mockgen.sh` script to regenerate mocks.
+
+## Conditional generation
+
+The `source` mode supports a way to conditionally regenerate the mock types only if the relevant source code has changed.
+It compares the modification time of mock file with its relevant source file to detect.
+
+[gomock]: https://github.com/golang/mock
+[mockgen modes]: https://github.com/golang/mock#running-mockgen

harness/attributes/common.yml

@@ -19,6 +19,10 @@ attributes.default:
     additional_binaries: []
     packages: []
     copy_files: []
+    mockgen:
+      mode: source
+      paths:
+        - source: "./test/example.go"
 
   domain: my127.site
   hostname: = @('namespace') ~ '.' ~ @('domain')

harness/config/confd.yml

@@ -2,6 +2,7 @@ confd('harness:/'):
   - { src: application/overlay/Jenkinsfile }
   - { src: application/skeleton/README.md }
   - { src: application/skeleton/.gitignore }
+  - { src: application/skeleton/tools/scripts/mockgen.sh, dst: workspace:/tools/scripts/mockgen.sh }
   - { src: docker/image/app/Dockerfile }
   - { src: docker/image/app/root/lib/task/gocyclo.sh }
   - { src: docker/image/app/root/lib/task/gosec.sh }

test

@@ -37,6 +37,8 @@ function test()
     fi
 
     ws helm kubeval qa
+    ws go generate
+    ws go test
 
     ws disable
     ws enable