versioning: adds tooling to compile a program against a given old CNI version

Allows us to write tests that cover interactions between components of
differing versions

pkg/version/testhelpers/testhelpers_test.go

@@ -0,0 +1,106 @@
+// Copyright 2016 CNI authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package testhelpers_test
+
+import (
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+
+	"github.com/containernetworking/cni/pkg/version/testhelpers"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("BuildAt", func() {
+	var (
+		gitRef         string
+		outputFilePath string
+		outputDir      string
+		programSource  []byte
+	)
+	BeforeEach(func() {
+		programSource = []byte(`package main
+
+import "github.com/containernetworking/cni/pkg/skel"
+
+func c(_ *skel.CmdArgs) error { return nil }
+
+func main() { skel.PluginMain(c, c) }
+`)
+		gitRef = "f4364185253"
+
+		var err error
+		outputDir, err = ioutil.TempDir("", "bin")
+		Expect(err).NotTo(HaveOccurred())
+		outputFilePath = filepath.Join(outputDir, "some-binary")
+	})
+
+	AfterEach(func() {
+		Expect(os.RemoveAll(outputDir)).To(Succeed())
+	})
+
+	It("builds the provided source code using the CNI library at the given git ref", func() {
+		Expect(outputFilePath).NotTo(BeAnExistingFile())
+
+		err := testhelpers.BuildAt(programSource, gitRef, outputFilePath)
+		Expect(err).NotTo(HaveOccurred())
+
+		Expect(outputFilePath).To(BeAnExistingFile())
+
+		cmd := exec.Command(outputFilePath)
+		cmd.Env = []string{"CNI_COMMAND=VERSION"}
+		output, err := cmd.CombinedOutput()
+		Expect(err).To(BeAssignableToTypeOf(&exec.ExitError{}))
+		Expect(output).To(ContainSubstring("unknown CNI_COMMAND: VERSION"))
+	})
+})
+
+var _ = Describe("LocateCurrentGitRepo", func() {
+	It("returns the path to the root of the CNI git repo", func() {
+		path, err := testhelpers.LocateCurrentGitRepo()
+		Expect(err).NotTo(HaveOccurred())
+
+		AssertItIsTheCNIRepoRoot(path)
+	})
+
+	Context("when run from a different directory", func() {
+		BeforeEach(func() {
+			os.Chdir("..")
+		})
+
+		It("still finds the CNI repo root", func() {
+			path, err := testhelpers.LocateCurrentGitRepo()
+			Expect(err).NotTo(HaveOccurred())
+
+			AssertItIsTheCNIRepoRoot(path)
+		})
+	})
+})
+
+func AssertItIsTheCNIRepoRoot(path string) {
+	Expect(path).To(BeADirectory())
+	files, err := ioutil.ReadDir(path)
+	Expect(err).NotTo(HaveOccurred())
+
+	names := []string{}
+	for _, file := range files {
+		names = append(names, file.Name())
+	}
+
+	Expect(names).To(ContainElement("SPEC.md"))
+	Expect(names).To(ContainElement("libcni"))
+	Expect(names).To(ContainElement("cnitool"))
+}