examples: review, testing and documentation (#176)

* examples reviews, testing and documentation

* including the execution on travis, and fix readme

* fix example link

* including the execution on travis

1 files changed, 105 insertions, 0 deletions

diff --git a/examples/common_test.go b/examples/common_test.go
new file mode 100644
index 0000000..1059f4b
--- /dev/null
+++ b/examples/common_test.go
@@ -0,0 +1,105 @@
+package examples
+
+import (
+	"flag"
+	"go/build"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"testing"
+)
+
+var examplesTest = flag.Bool("examples", false, "run the examples tests")
+
+var defaultURL = "https://github.com/mcuadros/basic.git"
+
+var args = map[string][]string{
+	"showcase":    []string{defaultURL},
+	"custom_http": []string{defaultURL},
+	"clone":       []string{defaultURL, tempFolder()},
+	"open":        []string{filepath.Join(cloneRepository(defaultURL, tempFolder()), ".git")},
+}
+
+var ignored = map[string]bool{
+	"storage": true,
+}
+
+var tempFolders = []string{}
+
+func TestExamples(t *testing.T) {
+	flag.Parse()
+	if !*examplesTest && os.Getenv("CI") == "" {
+		t.Skip("skipping examples tests, pass --examples to execute it")
+		return
+	}
+
+	defer deleteTempFolders()
+
+	examples, err := filepath.Glob(examplesFolder())
+	if err != nil {
+		t.Errorf("error finding tests: %s", err)
+	}
+
+	for _, example := range examples {
+		_, name := filepath.Split(filepath.Dir(example))
+
+		if ignored[name] {
+			continue
+		}
+
+		t.Run(name, func(t *testing.T) {
+			testExample(t, name, example)
+		})
+	}
+}
+
+func tempFolder() string {
+	path, err := ioutil.TempDir("", "")
+	CheckIfError(err)
+
+	tempFolders = append(tempFolders, path)
+	return path
+}
+
+func packageFolder() string {
+	return filepath.Join(
+		build.Default.GOPATH,
+		"src", "gopkg.in/src-d/go-git.v4",
+	)
+}
+
+func examplesFolder() string {
+	return filepath.Join(
+		packageFolder(),
+		"examples", "*", "main.go",
+	)
+}
+
+func cloneRepository(url, folder string) string {
+	cmd := exec.Command("git", "clone", url, folder)
+	err := cmd.Run()
+	CheckIfError(err)
+
+	return folder
+}
+
+func testExample(t *testing.T, name, example string) {
+	cmd := exec.Command("go", append([]string{
+		"run", filepath.Join(example),
+	}, args[name]...)...)
+
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+
+	if err := cmd.Run(); err != nil {
+		t.Errorf("error running cmd %q", err)
+	}
+}
+
+func deleteTempFolders() {
+	for _, folder := range tempFolders {
+		err := os.RemoveAll(folder)
+		CheckIfError(err)
+	}
+}