if a test is a modifier, ensure it includes valid sources

src/scribe/filecontent.go

@@ -55,6 +55,10 @@ func (f *FileContent) validate() error {
 	return nil
 }
 
+func (f *FileContent) isModifier() bool {
+	return false
+}
+
 func (f *FileContent) expandVariables(v []Variable) {
 	f.Path = variableExpansion(v, f.Path)
 	f.File = variableExpansion(v, f.File)

src/scribe/filename.go

@@ -23,6 +23,10 @@ type nameMatch struct {
 	match string
 }
 
+func (f *FileName) isModifier() bool {
+	return false
+}
+
 func (f *FileName) validate() error {
 	if len(f.Path) == 0 {
 		return fmt.Errorf("filename path must be set")

src/scribe/modifier.go

@@ -81,6 +81,10 @@ func (c *ConcatModifier) prepare() error {
 	return nil
 }
 
+func (c *ConcatModifier) isModifier() bool {
+	return true
+}
+
 func (c *ConcatModifier) validate() error {
 	if len(c.Operator) == 0 {
 		return fmt.Errorf("must specify concat operator")

src/scribe/package.go

@@ -20,6 +20,10 @@ type PackageInfo struct {
 	Version string
 }
 
+func (p *Package) isModifier() bool {
+	return false
+}
+
 func (p *Package) validate() error {
 	if len(p.Name) == 0 {
 		return fmt.Errorf("package must specify name")

src/scribe/test.go

@@ -64,6 +64,7 @@ type genericSource interface {
 	getCriteria() []EvaluationCriteria
 	expandVariables([]Variable)
 	validate() error
+	isModifier() bool
 }
 
 type genericEvaluator interface {
@@ -85,6 +86,18 @@ func (t *Test) validate(d *Document) error {
 	if err != nil {
 		return fmt.Errorf("%v: %v", t.Name, err)
 	}
+	// If this is a modifier, ensure the modifier sources are valid.
+	if si.isModifier() {
+		for _, x := range t.Modifier.Sources {
+			_, err := d.getTest(x.Name)
+			if err != nil {
+				return fmt.Errorf("%v: %v", t.Name, err)
+			}
+			if x.Select != "all" {
+				return fmt.Errorf("%v: modifier source must include selector", t.Name)
+			}
+		}
+	}
 	if t.getEvaluationInterface() == nil {
 		return fmt.Errorf("%v: no valid evaluation interface", t.Name)
 	}