diff --git a/lang/interpret_test.go b/lang/interpret_test.go
index d69f4513..09e78d71 100644
--- a/lang/interpret_test.go
+++ b/lang/interpret_test.go
@@ -547,6 +547,7 @@ func TestAstFunc0(t *testing.T) {
 func TestAstFunc1(t *testing.T) {
 	const magicError = "# err: "
 	const magicError1 = "err1: "
+	const magicErrorFailInit = "errInit: "
 	const magicError2 = "err2: "
 	const magicError3 = "err3: "
 	const magicError4 = "err4: "
@@ -578,10 +579,11 @@ func TestAstFunc1(t *testing.T) {
 	}
 
 	type errs struct {
-		fail1 bool
-		fail2 bool
-		fail3 bool
-		fail4 bool
+		fail1    bool
+		failInit bool
+		fail2    bool
+		fail3    bool
+		fail4    bool
 	}
 	type test struct { // an individual test
 		name string
@@ -635,6 +637,7 @@ func TestAstFunc1(t *testing.T) {
 		// if the graph file has a magic error string, it's a failure
 		errStr := ""
 		fail1 := false
+		failInit := false
 		fail2 := false
 		fail3 := false
 		fail4 := false
@@ -647,6 +650,11 @@ func TestAstFunc1(t *testing.T) {
 				str = errStr
 				fail1 = true
 			}
+			if strings.HasPrefix(str, magicErrorFailInit) {
+				errStr = strings.TrimPrefix(str, magicErrorFailInit)
+				str = errStr
+				failInit = true
+			}
 			if strings.HasPrefix(str, magicError2) {
 				errStr = strings.TrimPrefix(str, magicError2)
 				str = errStr
@@ -671,10 +679,11 @@ func TestAstFunc1(t *testing.T) {
 			fail:   errStr != "",
 			expstr: str,
 			errs: errs{
-				fail1: fail1,
-				fail2: fail2,
-				fail3: fail3,
-				fail4: fail4,
+				fail1:    fail1,
+				failInit: failInit,
+				fail2:    fail2,
+				fail3:    fail3,
+				fail4:    fail4,
 			},
 		})
 		//t.Logf("adding: %s", f + "/")
@@ -709,6 +718,7 @@ func TestAstFunc1(t *testing.T) {
 			name, path, fail, expstr, errs := tc.name, tc.path, tc.fail, strings.Trim(tc.expstr, "\n"), tc.errs
 			src := dir + path // location of the test
 			fail1 := errs.fail1
+			failInit := errs.failInit
 			fail2 := errs.fail2
 			fail3 := errs.fail3
 			fail4 := errs.fail4
@@ -818,11 +828,27 @@ func TestAstFunc1(t *testing.T) {
 				},
 			}
 			// some of this might happen *after* interpolate in SetScope or Unify...
-			if err := ast.Init(data); err != nil {
+			err = ast.Init(data)
+			if (!fail || !failInit) && err != nil {
 				t.Errorf("test #%d: FAIL", index)
 				t.Errorf("test #%d: could not init and validate AST: %+v", index, err)
 				return
 			}
+			if failInit && err != nil {
+				s := err.Error() // convert to string
+				if s != expstr {
+					t.Errorf("test #%d: FAIL", index)
+					t.Errorf("test #%d: expected different error", index)
+					t.Logf("test #%d: err: %s", index, s)
+					t.Logf("test #%d: exp: %s", index, expstr)
+				}
+				return
+			}
+			if failInit && err == nil {
+				t.Errorf("test #%d: FAIL", index)
+				t.Errorf("test #%d: functions passed, expected fail", index)
+				return
+			}
 
 			iast, err := ast.Interpolate()
 			if err != nil {