view: improve type assertions and handle stream write errors (#33)

* view: type assert the timestamp

* view: type assert the renderers

Apparently, the forcetypeassert linter wasn’t satisfied with relying on the type assertion from the assert package and required an explicit type assertion instead.

* view: panic when the underlying stream can't write

Previously, we were suppressing errors when writing to the underlying stream. While there’s no perfect way to handle this, panicking ensures that failures don’t go unnoticed.

Author: bschaatsbergen

internal/view/json_test.go

@@ -82,15 +82,22 @@ func testJSONViewOutputEqualsFull(t *testing.T, output string, want []map[string
 			t.Fatal(err)
 		}
 
+		// While we don't control this directly, we can at least ensure that the timestamp
+		// is present and correctly formatted, as expected.
+		// The timestamp is added by the logger, not the JSONView.
 		if timestamp, ok := gotStruct["@timestamp"]; !ok {
 			t.Errorf("message has no timestamp: %#v", gotStruct)
 		} else {
 			// Remove the timestamp value from the struct to allow comparison
 			delete(gotStruct, "@timestamp")
 
 			// Verify the timestamp format
-			if _, err := time.Parse(time.RFC3339, timestamp.(string)); err != nil {
-				t.Errorf("error parsing timestamp on line %d: %s", i, err)
+			if str, ok := timestamp.(string); ok {
+				if _, err := time.Parse(time.RFC3339, str); err != nil {
+					t.Errorf("error parsing timestamp on line %d: %s", i, err)
+				}
+			} else {
+				t.Errorf("unexpected type for timestamp on line %d: %T", i, timestamp)
 			}
 		}
 

internal/view/render.go

@@ -39,7 +39,10 @@ func NewHumanRenderer(view *View) *HumanRenderer {
 // Render renders a DNS record in human-readable format to the output stream.
 func (v *HumanRenderer) Render(domain string, record dns.RR) {
 	humanReadable := formatRecord(domain, record)
-	v.view.Stream.Writer.Write([]byte(humanReadable + "\n"))
+	_, err := v.view.Stream.Writer.Write([]byte(humanReadable + "\n"))
+	if err != nil {
+		panic(err)
+	}
 }
 
 // JSONRenderer for rendering JSON output.

internal/view/render_test.go

@@ -18,10 +18,13 @@ func TestNewRenderer_human(t *testing.T) {
 	hv := NewRenderer(arguments.ViewHuman, NewView(&b))
 
 	// Check that the view is a HumanRenderer
-	assert.IsType(t, &HumanRenderer{}, hv)
+	humanRenderer, ok := hv.(*HumanRenderer)
+	assert.True(t, ok, "Expected hv to be of type *HumanRenderer")
+
+	assert.IsType(t, &HumanRenderer{}, humanRenderer)
 
 	// Check that the view's stream writer is the same as the buffer
-	assert.Equal(t, &b, hv.(*HumanRenderer).view.Stream.Writer)
+	assert.Equal(t, &b, humanRenderer.view.Stream.Writer)
 }
 
 // TestNewHumanRenderer should simply return a HumanRenderer.
@@ -110,10 +113,11 @@ func TestNewRenderer_JSON(t *testing.T) {
 	jv := NewRenderer(arguments.ViewJSON, NewView(&b))
 
 	// Check that the view is a JSONRenderer
-	assert.IsType(t, &JSONRenderer{}, jv)
+	jsonRenderer, ok := jv.(*JSONRenderer)
+	assert.True(t, ok, "Expected jv to be of type *JSONRenderer")
 
 	// Check that the view's stream writer is the same as the buffer
-	assert.Equal(t, &b, jv.(*JSONRenderer).view.Stream.Writer)
+	assert.Equal(t, &b, jsonRenderer.view.Stream.Writer)
 }
 
 // TestNewJSONRenderer should simply return a JSONRenderer.