vault backup: 2025-05-20 07:19:33

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diff --git a/Redirecting output during testing.md b/Redirecting output during testing.md
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+---
+tags:
+  - golang
+  - testing
+---
+[[Testing Golang programs]]
+
+Some functions print or log to stdout/stderr, but during testing we would like to capture this. Here is an example of how to do that:
+```echo.go
+package echo
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"strings"
+)
+
+var out io.Writer = os.Stdout
+
+func echo() {
+	fmt.Fprintln(out, strings.Join(os.Args[1:], " "))
+}
+```
+
+We define an io.Writer at the package level which is used to write our output to. During tests we can set this to be a buffer, ie:
+
+```echo_test.go
+package echo
+
+import (
+	"bytes"
+	"testing"
+)
+
+func BenchmarkEcho(b *testing.B) {
+	out = new(bytes.Buffer)
+
+	for b.Loop() {
+		echo()
+	}
+}
+```
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