tests: integration tests for third-party packages (#112)

Closes #103

tests/thirdparty/config.go

@@ -0,0 +1,48 @@
+// Package thirdparty executes integration tests based on third-party packages that use avo.
+package thirdparty
+
+import (
+	"encoding/json"
+	"io"
+	"os"
+	"path/filepath"
+)
+
+// Package defines an integration test based on a third-party package using avo.
+type Package struct {
+	ImportPath string     `json:"import_path"` // package import path
+	Version    string     `json:"version"`     // git sha, tag or branch
+	Generate   [][]string `json:"generate"`    // generate commands to run
+	Dir        string     `json:"dir"`         // working directory for generate commands
+}
+
+// Name returns the package name.
+func (p Package) Name() string {
+	return filepath.Base(p.ImportPath)
+}
+
+// CloneURL returns the git clone URL.
+func (p Package) CloneURL() string {
+	return "https://" + p.ImportPath + ".git"
+}
+
+// LoadPackages loads a list of package configurations from JSON format.
+func LoadPackages(r io.Reader) ([]Package, error) {
+	var pkgs []Package
+	d := json.NewDecoder(r)
+	d.DisallowUnknownFields()
+	if err := d.Decode(&pkgs); err != nil {
+		return nil, err
+	}
+	return pkgs, nil
+}
+
+// LoadPackagesFile loads a list of package configurations from a JSON file.
+func LoadPackagesFile(filename string) ([]Package, error) {
+	f, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+	return LoadPackages(f)
+}