fix: check for extra variables defined in tests

examples/with-tests/tests/bar/test.yml

@@ -1,3 +1,2 @@
 values:
   MY_VAR: bar
-ignoreExtraFiles: false

examples/with-tests/tests/foo/test.yml

@@ -1,3 +1,2 @@
 values:
   MY_VAR: foo
-ignoreExtraFiles: false

pkg/recipe/recipe.go

@@ -24,27 +24,41 @@ func (re *Recipe) Validate() error {
 		return err
 	}
 
-	checkDuplicates := make(map[string]bool)
+	varDuplicateCheck := make(map[string]struct{})
 	for _, v := range re.Variables {
+		if _, exists := varDuplicateCheck[v.Name]; exists {
+			return fmt.Errorf("variable %s has been declared multiple times", v.Name)
+		}
 		if err := v.Validate(); err != nil {
 			return fmt.Errorf("error on variable %s: %w", v.Name, err)
 		}
-		if _, exists := checkDuplicates[v.Name]; exists {
-			return fmt.Errorf("variable %s has been declared multiple times", v.Name)
-		}
-		checkDuplicates[v.Name] = true
+		varDuplicateCheck[v.Name] = struct{}{}
 	}
 
-	duplicateCheck := make(map[string]struct{})
+	testDuplicateCheck := make(map[string]struct{})
 	for _, t := range re.Tests {
-		if _, exists := duplicateCheck[t.Name]; exists {
+		if _, exists := testDuplicateCheck[t.Name]; exists {
 			return fmt.Errorf("test case %s has been declared multiple times", t.Name)
 		}
 
-		duplicateCheck[t.Name] = struct{}{}
 		if err := t.Validate(); err != nil {
 			return fmt.Errorf("error when validating recipe test case %s: %w", t.Name, err)
 		}
+		testDuplicateCheck[t.Name] = struct{}{}
+
+		for vName := range t.Values {
+			found := false
+			for _, v := range re.Variables {
+				if v.Name == vName {
+					found = true
+					break
+				}
+			}
+
+			if !found {
+				return fmt.Errorf("test case %s references an unknown variable %s", t.Name, vName)
+			}
+		}
 	}
 
 	return nil

pkg/recipe/test_test.go

@@ -192,6 +192,14 @@ func TestRecipeTests(t *testing.T) {
 			recipe.Tests = tests
 			recipe.Templates = scenario.templates
 
+			for _, t := range recipe.Tests {
+				for vName := range t.Values {
+					recipe.Variables = append(recipe.Variables, Variable{
+						Name: vName,
+					})
+				}
+			}
+
 			errs := recipe.RunTests()
 			for i, err := range errs {
 				expectedErr := scenario.tests[i].ExpectedError