Standardize Go-package structure (#746)

regression_test.go

@@ -0,0 +1,70 @@
+package main
+
+import (
+	"fmt"
+	"os"
+	"testing"
+
+	"mlr/internal/pkg/auxents/regtest"
+)
+
+// TestRegression is a familiar entry point for regression testing.  Miller
+// regression tests are more flexibly invoked via 'mlr regtest'.  However here
+// is a standard location so people can get at them via 'go test'.  Please see
+// (as of this writing) src/auxents/regtest for the Miller regtest package.
+func TestRegression(t *testing.T) {
+	// How much detail to show?  There are thousands of cases, organized into a
+	// few hundred top-level directories under ./test/cases.
+	//
+	// Default behavior is to show PASS/FAIL for those top-level directories.
+	// If (for whatever reason) lots of tests are systematically failing then
+	// verbosityLevel = 3 for all cases is probably too much output to be
+	// useful.
+	//
+	// Also note our regtest framework supports four verbosity levels, 'mlr
+	// regtest' (0) through 'mlr regtest -vvv' (3), while 'go test' has only
+	// 'go test' and 'go test -v'. Our regtest framework also has 'mlr regtest
+	// -s 20' which means *re-run* up to 20 failing tests (after having failed
+	// once with verbosityLevel = 0) as if those had been invoked with
+	// verbosityLevel = 3.
+	//
+	// What we do is:
+	// * go test:    like 'mlr regtest'
+	// * go test -v: like 'mlr regtest -s 20'
+	//
+	// This is (I hope) sufficient flexibility for use in GitHub Actions
+	// continuous-integration jobs. If more detail is needed then one may:
+	//
+	// * For CI debugging: simply edit the below parameters verbosityLevel
+	//   and firstNFailsToShow and re-push to GitHub.
+	// * For interactive debug: run 'mlr regtest -v', 'mlr regtest -vv', 'mlr
+	//   regtest -vvv' instead of going through 'go test'.
+	firstNFailsToShow := 0
+	if testing.Verbose() {
+		firstNFailsToShow = 20
+	}
+
+	// Let the tests find ./mlr
+	cwd, err := os.Getwd()
+	if err != nil {
+		fmt.Fprintln(os.Stderr, "mlr: could not find current working directory.")
+		os.Exit(1)
+	}
+	path := os.Getenv("PATH")
+	os.Setenv("PATH", cwd+":"+path)
+
+	regtester := regtest.NewRegTester(
+		"mlr", // exeName
+		false, // doPopulate
+		0,     // verbosityLevel
+		false, // plainMode
+		firstNFailsToShow,
+	)
+
+	paths := []string{} // use default
+
+	ok := regtester.Execute(paths)
+	if !ok {
+		t.Fatal()
+	}
+}