read: test reading specific document of multidocument

.gitignore

@@ -36,3 +36,4 @@ parts/
 prime/
 .snapcraft/
 yq*.snap
+*.swp

examples/multidocument.yaml

@@ -0,0 +1,9 @@
+---
+a: Document One
+b:
+  c: 1
+---
+a: Document Two
+b:
+  c: 2
+

utils_test.go

@@ -60,6 +60,12 @@ func assertResultWithContext(t *testing.T, expectedValue interface{}, actualValu
 	}
 }
 
+func assertAnyErr(t *testing.T, actualValue error) {
+	if actualValue == nil {
+		t.Error("Expected error, got nil")
+	}
+}
+
 func writeTempYamlFile(content string) string {
 	tmpfile, _ := ioutil.TempFile("", "testyaml")
 	defer func() {

yq_test.go

@@ -38,6 +38,23 @@ func TestReadString(t *testing.T) {
 	assertResult(t, "hi", result)
 }
 
+func TestReadMultipleDocuments(t *testing.T) {
+	t.Run("multiple documents assumes first", func(t *testing.T) {
+		result, _ := read([]string{"examples/multidocument.yaml", "b.c"})
+		assertResult(t, 1, result)
+	})
+	t.Run("multiple documents with leading @n reads from document n", func(t *testing.T) {
+		result, _ := read([]string{"examples/multidocument.yaml", "@0.b.c"})
+		assertResult(t, 1, result)
+
+		result, _ = read([]string{"examples/multidocument.yaml", "@1.b.c"})
+		assertResult(t, 2, result)
+
+		_, err := read([]string{"examples/multidocument.yaml", "@2.b.c"})
+		assertAnyErr(t, err)
+	})
+}
+
 func TestOrder(t *testing.T) {
 	result, _ := read([]string{"examples/order.yaml"})
 	formattedResult, _ := yamlToString(result)