add tests for info sharing

packer/build.go

@@ -163,7 +163,7 @@ func (b *CoreBuild) Prepare() (warn []string, err error) {
 	generatedPlaceholderMap := BasicPlaceholderData()
 	if generatedVars != nil {
 		for _, k := range generatedVars {
-			generatedPlaceholderMap[k] = fmt.Sprintf("Generated_%s. "+
+			generatedPlaceholderMap[k] = fmt.Sprintf("Build_%s. "+
 				common.PlaceholderMsg, k)
 		}
 	}

packer/build_test.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"reflect"
 	"testing"
+
+	"github.com/hashicorp/packer/helper/common"
 )
 
 func boolPointer(tf bool) *bool {
@@ -176,6 +178,34 @@ func TestBuildPrepare_variables_default(t *testing.T) {
 	}
 }
 
+func TestBuildPrepare_ProvisionerGetsGeneratedMap(t *testing.T) {
+	packerConfig := testDefaultPackerConfig()
+
+	build := testBuild()
+	builder := build.Builder.(*MockBuilder)
+	builder.GeneratedVars = []string{"PartyVar"}
+
+	build.Prepare()
+	if !builder.PrepareCalled {
+		t.Fatalf("should be called")
+	}
+	if !reflect.DeepEqual(builder.PrepareConfig, []interface{}{42, packerConfig}) {
+		t.Fatalf("bad: %#v", builder.PrepareConfig)
+	}
+
+	coreProv := build.Provisioners[0]
+	prov := coreProv.Provisioner.(*MockProvisioner)
+	if !prov.PrepCalled {
+		t.Fatal("prepare should be called")
+	}
+
+	generated := BasicPlaceholderData()
+	generated["PartyVar"] = "Build_PartyVar. " + common.PlaceholderMsg
+	if !reflect.DeepEqual(prov.PrepConfigs, []interface{}{42, packerConfig, generated}) {
+		t.Fatalf("bad: %#v", prov.PrepConfigs)
+	}
+}
+
 func TestBuild_Run(t *testing.T) {
 	ui := testUi()
 

packer/builder_mock.go

@@ -25,6 +25,8 @@ type MockBuilder struct {
 	RunUi         Ui
 	CancelCalled  bool
 	RunFn         func(ctx context.Context)
+
+	GeneratedVars []string
 }
 
 func (tb *MockBuilder) ConfigSpec() hcldec.ObjectSpec { return tb.FlatMapstructure().HCL2Spec() }
@@ -34,7 +36,7 @@ func (tb *MockBuilder) FlatConfig() interface{} { return tb.FlatMapstructure() }
 func (tb *MockBuilder) Prepare(config ...interface{}) ([]string, []string, error) {
 	tb.PrepareCalled = true
 	tb.PrepareConfig = config
-	return nil, tb.PrepareWarnings, nil
+	return tb.GeneratedVars, tb.PrepareWarnings, nil
 }
 
 func (tb *MockBuilder) Run(ctx context.Context, ui Ui, h Hook) (Artifact, error) {

template/interpolate/funcs_test.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"github.com/google/go-cmp/cmp"
+	"github.com/hashicorp/packer/helper/common"
 	"github.com/hashicorp/packer/version"
 )
 
@@ -318,6 +319,90 @@ func TestFuncUser(t *testing.T) {
 	}
 }
 
+func TestFuncPackerBuild(t *testing.T) {
+	type cases struct {
+		DataMap     interface{}
+		ErrExpected bool
+		Template    string
+		OutVal      string
+	}
+
+	testCases := []cases{
+		// Data map is empty; there should be an error.
+		{
+			DataMap:     nil,
+			ErrExpected: true,
+			Template:    "{{ build `PartyVar` }}",
+			OutVal:      "",
+		},
+		// Data map is a map[string]string and contains value
+		{
+			DataMap:     map[string]string{"PartyVar": "PartyVal"},
+			ErrExpected: false,
+			Template:    "{{ build `PartyVar` }}",
+			OutVal:      "PartyVal",
+		},
+		// Data map is a map[string]string and contains value
+		{
+			DataMap:     map[string]string{"PartyVar": "PartyVal"},
+			ErrExpected: false,
+			Template:    "{{ build `PartyVar` }}",
+			OutVal:      "PartyVal",
+		},
+		// Data map is a map[string]string and contains value with placeholder.
+		{
+			DataMap:     map[string]string{"PartyVar": "PartyVal" + common.PlaceholderMsg},
+			ErrExpected: false,
+			Template:    "{{ build `PartyVar` }}",
+			OutVal:      "{{.PartyVar}}",
+		},
+		// Data map is a map[interface{}]interface{} and contains value
+		{
+			DataMap:     map[interface{}]interface{}{"PartyVar": "PartyVal"},
+			ErrExpected: false,
+			Template:    "{{ build `PartyVar` }}",
+			OutVal:      "PartyVal",
+		},
+		// Data map is a map[interface{}]interface{} and contains value
+		{
+			DataMap:     map[interface{}]interface{}{"PartyVar": "PartyVal"},
+			ErrExpected: false,
+			Template:    "{{ build `PartyVar` }}",
+			OutVal:      "PartyVal",
+		},
+		// Data map is a map[interface{}]interface{} and contains value with placeholder.
+		{
+			DataMap:     map[interface{}]interface{}{"PartyVar": "PartyVal" + common.PlaceholderMsg},
+			ErrExpected: false,
+			Template:    "{{ build `PartyVar` }}",
+			OutVal:      "{{.PartyVar}}",
+		},
+		// Data map is a map[interface{}]interface{} and doesn't have value.
+		{
+			DataMap:     map[interface{}]interface{}{"BadVar": "PartyVal" + common.PlaceholderMsg},
+			ErrExpected: true,
+			Template:    "{{ build `MissingVar` }}",
+			OutVal:      "",
+		},
+	}
+
+	for _, tc := range testCases {
+		ctx := &Context{}
+		ctx.Data = tc.DataMap
+		i := &I{Value: tc.Template}
+
+		result, err := i.Render(ctx)
+		if (err != nil) != tc.ErrExpected {
+			t.Fatalf("Input: %s\n\nerr: %s", tc.Template, err)
+		}
+
+		if ok := strings.Compare(result, tc.OutVal); ok != 0 {
+			t.Fatalf("Expected input to include: %s\n\nGot: %s",
+				tc.OutVal, result)
+		}
+	}
+}
+
 func TestFuncPackerVersion(t *testing.T) {
 	template := `{{packer_version}}`