fix(cnbBuild): allow setting empty env variables in project descriptor (#4084)

cmd/cnbBuild_test.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"net/http"
+	"path/filepath"
 	"testing"
 
 	"github.com/SAP/jenkins-library/pkg/cnbutils"
@@ -58,6 +59,14 @@ func assertLifecycleCalls(t *testing.T, runner *mock.ExecMockRunner, callNo int)
 	}
 }
 
+func assetBuildEnv(t *testing.T, utils cnbutils.MockUtils, key, value string) bool {
+	env, err := utils.FilesMock.ReadFile(filepath.Join("/tmp/platform/env/", key))
+	if !assert.NoError(t, err) {
+		return false
+	}
+	return assert.Equal(t, value, string(env))
+}
+
 func TestRunCnbBuild(t *testing.T) {
 	configOptions.openFile = piperconf.OpenPiperFile
 
@@ -283,6 +292,46 @@ func TestRunCnbBuild(t *testing.T) {
 		assert.Contains(t, runner.Calls[0].Params, fmt.Sprintf("%s/%s:3.1.5", config.ContainerRegistryURL, config.ContainerImageName))
 	})
 
+	t.Run("success case: build environment variables", func(t *testing.T) {
+		t.Parallel()
+		commonPipelineEnvironment := cnbBuildCommonPipelineEnvironment{}
+		config := cnbBuildOptions{
+			ContainerImageTag:    "0.0.1",
+			ContainerRegistryURL: fmt.Sprintf("https://%s", imageRegistry),
+			ProjectDescriptor:    "project.toml",
+			BuildEnvVars: map[string]interface{}{
+				"OPTIONS_KEY": "OPTIONS_VALUE",
+				"OVERWRITE":   "this should win",
+			},
+		}
+
+		projectToml := `[project]
+		id = "io.buildpacks.my-app"
+
+		[[build.env]]
+		name="PROJECT_DESCRIPTOR_KEY"
+		value="PROJECT_DESCRIPTOR_VALUE"
+
+		[[build.env]]
+		name="OVERWRITE"
+		value="this should be overwritten"
+		`
+
+		utils := newCnbBuildTestsUtils()
+		utils.FilesMock.AddFile("project.toml", []byte(projectToml))
+		addBuilderFiles(&utils)
+
+		telemetryData := telemetry.CustomData{}
+		err := callCnbBuild(&config, &telemetryData, &utils, &commonPipelineEnvironment, &piperhttp.Client{})
+
+		require.NoError(t, err)
+		assertLifecycleCalls(t, utils.ExecMockRunner, 1)
+
+		assetBuildEnv(t, utils, "OPTIONS_KEY", "OPTIONS_VALUE")
+		assetBuildEnv(t, utils, "PROJECT_DESCRIPTOR_KEY", "PROJECT_DESCRIPTOR_VALUE")
+		assetBuildEnv(t, utils, "OVERWRITE", "this should win")
+	})
+
 	t.Run("pom.xml exists (symlink for the target folder)", func(t *testing.T) {
 		t.Parallel()
 		config := cnbBuildOptions{

pkg/cnbutils/project/descriptor.go

@@ -104,7 +104,7 @@ func (b *build) envToMap() map[string]interface{} {
 	envMap := map[string]interface{}{}
 
 	for _, e := range b.Env {
-		if len(e.Name) == 0 || len(e.Value) == 0 {
+		if len(e.Name) == 0 {
 			continue
 		}
 

pkg/cnbutils/project/descriptor_test.go

@@ -34,6 +34,10 @@ value = "VAL1"
 name = "VAR2"
 value = "VAL2"
 
+[[build.env]]
+name = "EMPTY"
+value = ""
+
 [[build.buildpacks]]
 id = "paketo-buildpacks/java"
 version = "5.9.1"
@@ -64,6 +68,7 @@ id = "paketo-buildpacks/nodejs"
 		assert.NoError(t, err)
 		assert.Equal(t, descriptor.EnvVars["VAR1"], "VAL1")
 		assert.Equal(t, descriptor.EnvVars["VAR2"], "VAL2")
+		assert.Equal(t, descriptor.EnvVars["EMPTY"], "")
 
 		assert.Equal(t, descriptor.ProjectID, "io.buildpacks.my-app")