factor(go): setup testable exam

go/.gitignore

@@ -0,0 +1,32 @@
+# If you prefer the allow list template instead of the deny list, see community template:
+# https://github.com/github/gitignore/blob/main/community/Golang/Go.AllowList.gitignore
+#
+# Binaries for programs and plugins
+*.exe
+*.exe~
+*.dll
+*.so
+*.dylib
+
+# Test binary, built with `go test -c`
+*.test
+
+# Code coverage profiles and other test artifacts
+*.out
+coverage.*
+*.coverprofile
+profile.cov
+
+# Dependency directories (remove the comment below to include it)
+# vendor/
+
+# Go workspace file
+go.work
+go.work.sum
+
+# env file
+.env
+
+# Editor/IDE
+# .idea/
+# .vscode/

go/exam/exam.go

@@ -68,9 +68,9 @@ func getAll(nums []int64, ops []byte) []Pair {
 	return result
 }
 
-func main() {
-	reader := bufio.NewReader(os.Stdin)
-	writer := bufio.NewWriter(os.Stdout)
+func exam(in *os.File, out *os.File) {
+	reader := bufio.NewReader(in)
+	writer := bufio.NewWriter(out)
 	defer writer.Flush()
 
 	var n int
@@ -136,3 +136,7 @@ func main() {
 		fmt.Fprintln(writer, "NO SOLUTION")
 	}
 }
+
+func main() {
+	exam(os.Stdin, os.Stdout)
+}

go/exam/exam_test.go

@@ -0,0 +1,82 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func runTest(testcase string) func(t *testing.T) {
+	return func(t *testing.T) {
+		inPath := filepath.Join("in", testcase+".txt")
+		outPath := filepath.Join("out", testcase+".txt")
+		expectPath := filepath.Join("expected", testcase+".txt")
+
+		inFile, err := os.Open(inPath)
+		if err != nil {
+			t.Fatal(err)
+		}
+		outFile, err := os.Create(outPath)
+		if err != nil {
+			t.Fatal(err)
+		}
+		exam(inFile, outFile)
+
+		actual, err := os.ReadFile(outPath)
+		if err != nil {
+			t.Fatalf("cannot read output file: %v", err)
+		}
+
+		expected, err := os.ReadFile(expectPath)
+		if err != nil {
+			t.Fatalf("cannot read expected file: %v", err)
+		}
+
+		actualLines := strings.Split(strings.ReplaceAll(string(actual), "\r\n", "\n"), "\n")
+		expectedLines := strings.Split(strings.ReplaceAll(string(expected), "\r\n", "\n"), "\n")
+
+		maxLen := max(len(actualLines), len(expectedLines))
+
+		for i := 0; i < maxLen; i++ {
+			var a, e string
+			if i < len(actualLines) {
+				a = actualLines[i]
+			}
+			if i < len(expectedLines) {
+				e = expectedLines[i]
+			}
+
+			if a != e {
+				t.Fatalf(
+					"difference at line %d\nexpected: %q\nactual:   %q\n",
+					i+1,
+					e,
+					a,
+				)
+			}
+		}
+
+	}
+}
+
+func TestRunFromFiles(t *testing.T) {
+	files, err := os.ReadDir("in")
+	if err != nil {
+		t.Fatalf("cannot read in dir %v", err)
+	}
+
+	if err := os.MkdirAll("out", 0755); err != nil {
+		t.Fatalf("cannot create out dir: %v", err)
+	}
+
+	for _, f := range files {
+		if f.IsDir() || !strings.HasSuffix(f.Name(), ".txt") {
+			continue
+		}
+
+		testcase := strings.TrimSuffix(f.Name(), ".txt")
+
+		t.Run(testcase, runTest(testcase))
+	}
+}

go/exam/expected/.gitignore

@@ -0,0 +1,2 @@
+*
+!.gitignore

go/exam/go.mod

@@ -0,0 +1,3 @@
+module exam
+
+go 1.23.4

go/exam/go.work

@@ -0,0 +1,3 @@
+go 1.23.4
+
+use .

go/exam/in/.gitignore

@@ -0,0 +1,2 @@
+*
+!.gitignore

go/exam/out/.gitignore

@@ -0,0 +1,2 @@
+*
+!.gitignore