Deploy main eacf1e7 to prod

Replaces #559, which conflicted.

Model: opus-5-5

internal/config/dotenv_test.go

@@ -8,6 +8,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"sneak.berlin/go/webhooker/internal/config"
+	"sneak.berlin/go/webhooker/internal/config/configtest"
 )
 
 // dotEnvKey is a throwaway variable name the .env tests write and
@@ -22,17 +23,6 @@ const malformedDotEnv = "PORT 19615\n" +
 	"this is not = valid ! syntax\n" +
 	"\"unclosed\n"
 
-// unsetDotEnvKey makes dotEnvKey genuinely absent for the duration of
-// the test and restores it afterwards. t.Setenv registers the restore;
-// the Unsetenv that follows is what the test actually needs, because a
-// variable set to the empty string is still present in os.Environ and
-// godotenv would refuse to overwrite it.
-func unsetDotEnvKey(t *testing.T) {
-	t.Helper()
-	t.Setenv(dotEnvKey, "placeholder")
-	require.NoError(t, os.Unsetenv(dotEnvKey))
-}
-
 // writeDotEnv writes contents to a .env file in a fresh temporary
 // directory and returns its path.
 func writeDotEnv(t *testing.T, contents string) string {
@@ -50,9 +40,9 @@ func writeDotEnv(t *testing.T, contents string) string {
 // normally rather than be refused for a file it was never meant to
 // have.
 //
-//nolint:paralleltest // unsetDotEnvKey uses t.Setenv.
+//nolint:paralleltest // ClearEnv uses t.Setenv.
 func TestLoadDotEnv_MissingFileIsFine(t *testing.T) {
-	unsetDotEnvKey(t)
+	configtest.ClearEnv(t)
 
 	absent := filepath.Join(t.TempDir(), config.DotEnvPath)
 	require.NoError(t, config.LoadDotEnvFileForTest(absent))
@@ -65,9 +55,9 @@ func TestLoadDotEnv_MissingFileIsFine(t *testing.T) {
 // reaches the environment, which is the whole reason the file is read
 // at all.
 //
-//nolint:paralleltest // unsetDotEnvKey uses t.Setenv.
+//nolint:paralleltest // ClearEnv uses t.Setenv.
 func TestLoadDotEnv_AppliesValues(t *testing.T) {
-	unsetDotEnvKey(t)
+	configtest.ClearEnv(t)
 
 	path := writeDotEnv(t, "# a comment\n"+dotEnvKey+"=from-dot-env\n")
 
@@ -93,9 +83,9 @@ func TestLoadDotEnv_RealEnvironmentWins(t *testing.T) {
 // reverts to its default; the process used to start that way with no
 // log line naming the file at all.
 //
-//nolint:paralleltest // unsetDotEnvKey uses t.Setenv.
+//nolint:paralleltest // ClearEnv uses t.Setenv.
 func TestLoadDotEnv_MalformedFileAborts(t *testing.T) {
-	unsetDotEnvKey(t)
+	configtest.ClearEnv(t)
 
 	path := writeDotEnv(
 		t, malformedDotEnv+dotEnvKey+"=from-dot-env\n",
@@ -143,7 +133,7 @@ func TestLoadDotEnv_UnreadableFileAborts(t *testing.T) {
 //
 //nolint:paralleltest // t.Chdir moves the whole process.
 func TestLoadDotEnv_ReadsTheWorkingDirectory(t *testing.T) {
-	unsetDotEnvKey(t)
+	configtest.ClearEnv(t)
 
 	dir := t.TempDir()
 	require.NoError(t, os.WriteFile(