Better error message when plugin cannot be found

pkg/invoke/find_test.go

@@ -0,0 +1,64 @@
+package invoke_test
+
+import (
+	"fmt"
+	"io/ioutil"
+	"path/filepath"
+
+	"github.com/appc/cni/pkg/invoke"
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("FindInPath", func() {
+	var (
+		multiplePaths  []string
+		pluginName     string
+		pluginDir      string
+		anotherTempDir string
+	)
+
+	BeforeEach(func() {
+		tempDir, err := ioutil.TempDir("", "cni-find")
+		Expect(err).NotTo(HaveOccurred())
+
+		plugin, err := ioutil.TempFile(tempDir, "a-cni-plugin")
+
+		anotherTempDir, err = ioutil.TempDir("", "nothing-here")
+
+		multiplePaths = []string{anotherTempDir, tempDir}
+		pluginDir, pluginName = filepath.Split(plugin.Name())
+	})
+
+	Context("when multiple paths are provided", func() {
+		It("returns only the path to the plugin", func() {
+			pluginPath, err := invoke.FindInPath(pluginName, multiplePaths)
+			Expect(err).NotTo(HaveOccurred())
+			Expect(pluginPath).To(Equal(filepath.Join(pluginDir, pluginName)))
+		})
+	})
+
+	Context("when an error occurs", func() {
+		Context("when no paths are provided", func() {
+			It("returns an error noting no paths were provided", func() {
+				_, err := invoke.FindInPath(pluginName, []string{})
+				Expect(err).To(MatchError("no paths provided"))
+			})
+		})
+
+		Context("when no plugin is provided", func() {
+			It("returns an error noting the plugin name wasn't found", func() {
+				_, err := invoke.FindInPath("", multiplePaths)
+				Expect(err).To(MatchError("no plugin name provided"))
+			})
+		})
+
+		Context("when the plugin cannot be found", func() {
+			It("returns an error noting the path", func() {
+				pathsWithNothing := []string{anotherTempDir}
+				_, err := invoke.FindInPath(pluginName, pathsWithNothing)
+				Expect(err).To(MatchError(fmt.Sprintf("failed to find plugin %q in path %s", pluginName, pathsWithNothing)))
+			})
+		})
+	})
+})