Create a TestFollow integration test

tailer_test.go

@@ -0,0 +1,91 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"github.com/cskr/pubsub"
+	"github.com/fatih/color"
+	"os"
+	"testing"
+	"time"
+)
+
+// writeALine writes a logString line to a specified logFilePath
+func writeALine(t *testing.T, logFilePath string, logString string) {
+	// Write a line to the logFilePath
+	file, err := os.OpenFile(logFilePath, os.O_CREATE|os.O_APPEND, 0644)
+	if err != nil {
+		t.Fatalf("failed creating file: %s", err)
+	}
+	datawriter := bufio.NewWriter(file)
+	datawriter.WriteString(fmt.Sprint(logString))
+	datawriter.Flush()
+	file.Close()
+}
+
+// TestFollow is an integration test for the entire backend tailing system
+//
+//	This test starts up the Follow function, which watches a specified log file,
+//	writes a line to the log file,
+//	and listens for a response on the pubsub topic.
+//	This test also verifies the message was correctly colored.
+func TestFollow(t *testing.T) {
+	// Enable ANSI colors regardless of terminal state
+	color.NoColor = false
+
+	// Load in the default config file, so we get some regex patterns
+	HandleConfigFile("logstation.default.conf")
+
+	// Get the compiledRegexColors
+	compiledRegexColors := ParseRegexPatterns()
+
+	// Prepare a colored string to compare to
+	testLine := "[INFO]: You might want to know about this..."
+	colored := fmt.Sprintf("\x1b[%dm%s\x1b[0m", color.FgHiGreen, testLine)
+	escapedForm := fmt.Sprintf("%q", colored)
+
+	// Log file to test against
+	logFilePath := "logfile.log"
+
+	// Setup message broker
+	pubSub := pubsub.New(1)
+
+	// Subscribe to "lines" topic
+	linesChannel := pubSub.Sub("lines")
+	defer pubSub.Unsub(linesChannel, "lines")
+
+	// Run Follow
+	go Follow(logFilePath, pubSub, compiledRegexColors)
+
+	// Give the fswatcher.RunFileTailer enough time to startup
+	time.Sleep(time.Duration(1000) * time.Millisecond)
+
+	// Write a line to the test log
+	writeALine(t, logFilePath, "[INFO]: You might want to know about this...\n")
+
+	// Setup a timer for listening to the topic
+	listenDurationString := "2s"
+	listenDuration, _ := time.ParseDuration(listenDurationString)
+	listenTimer := time.AfterFunc(listenDuration, func() {
+		t.Errorf("Waited %s for a message from Follow() and nothing came through. It's possible the tailer didn't get enough time to start tailing, or other bad things happened", listenDurationString)
+		// Let the test listener know that we're shutting things down
+		pubSub.Pub("poisonpill", "lines")
+	})
+	defer listenTimer.Stop()
+
+	// Listen for a response
+	for line := range linesChannel {
+		if line == "poisonpill" {
+			break // The test failed because we didn't get a message in the listenDuration
+		}
+
+		// Prepare the tailedLine for comparison
+		tailedLine := fmt.Sprintf("%q", line.(LogMessage).Text)
+
+		// Check to see if it matches expectations
+		if tailedLine != escapedForm {
+			t.Errorf("Expecting %s, got '%s'\n", escapedForm, tailedLine)
+		}
+		break
+	}
+}