Display error when --path is invalid

build.go

@@ -123,6 +123,16 @@ func (bf *BuildFactory) BuildConfigFromFlags(ctx context.Context, f *BuildFlags)
 	if err != nil {
 		return nil, err
 	}
+	stat, err := os.Stat(appDir)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, errors.Errorf("app directory %s does not exist", style.Symbol(appDir))
+		} else {
+			return nil, err
+		}
+	} else if !stat.IsDir() {
+		return nil, errors.Errorf("provided app directory %s is not a directory", style.Symbol(appDir))
+	}
 
 	f.RepoName = calculateRepositoryName(appDir, f)
 

build_test.go

@@ -7,6 +7,7 @@ import (
 	"io/ioutil"
 	"math/rand"
 	"os"
+	"path/filepath"
 	"testing"
 	"time"
 
@@ -368,5 +369,40 @@ PATH
 			})
 			h.AssertNotEq(t, os.Getenv("PATH"), "")
 		})
+
+		when("app path is invalid", func() {
+			when("app directory does not exist", func() {
+				it("return error", func() {
+					appDir := filepath.Join("testdata", "does-not-exist")
+
+					config, err := factory.BuildConfigFromFlags(context.TODO(), &pack.BuildFlags{
+						RepoName: "some/app",
+						Builder:  "some/builder",
+						AppDir:   appDir,
+					})
+
+					h.AssertNil(t, config)
+					h.AssertNotNil(t, err)
+					h.AssertContainsMatch(t, err.Error(), "^app directory .*does-not-exist.* does not exist$")
+				})
+			})
+
+			when("app directory is a file", func() {
+				it("return error", func() {
+					appDir := filepath.Join("testdata", "just-a-file.txt")
+
+					config, err := factory.BuildConfigFromFlags(context.TODO(), &pack.BuildFlags{
+						RepoName: "some/app",
+						Builder:  "some/builder",
+						AppDir:   appDir,
+					})
+
+					h.AssertNil(t, config)
+					h.AssertNotNil(t, err)
+
+					h.AssertContainsMatch(t, err.Error(), "^provided app directory .*just-a-file.txt.* is not a directory$")
+				})
+			})
+		})
 	}, spec.Parallel())
 }

run_test.go

@@ -81,15 +81,15 @@ func testRun(t *testing.T, when spec.G, it spec.S) {
 
 			run, err := factory.RunConfigFromFlags(context.TODO(), &pack.RunFlags{
 				BuildFlags: pack.BuildFlags{
-					AppDir:   "acceptance/testdata/node_app",
+					AppDir:   "testdata/some-app",
 					Builder:  "some/builder",
 					RunImage: "some/run",
 				},
 				Ports: []string{"1370"},
 			})
 			h.AssertNil(t, err)
 
-			absAppDir, _ := filepath.Abs("acceptance/testdata/node_app")
+			absAppDir, _ := filepath.Abs("testdata/some-app")
 			absAppDirMd5 := fmt.Sprintf("pack.local/run/%x", md5.Sum([]byte(absAppDir)))
 			h.AssertEq(t, run.RepoName, absAppDirMd5)
 			h.AssertEq(t, run.Ports, []string{"1370"})

testdata/some-app/.gitignore

@@ -0,0 +1 @@
+!.gitignore