build: only test internal/

Makefile

@@ -8,7 +8,7 @@ build:
 	@$(GO) build -o $(BIN) ./cmd/aoc
 
 test:
-	@$(GO) test ./...
+	@$(GO) test ./internal/...
 
 clean:
 	@rm -f $(BIN)

internal/2018/DayTwo/code_test.go

@@ -1,8 +1,14 @@
 package daytwo
 
-import "testing"
+import (
+	"bytes"
+	"os"
+	"strings"
+	"testing"
+)
 
-var testInput = []string{
+func TestPartOne(t *testing.T) {
+	input := []string{
 		"abcdef",
 		"bababc",
 		"abbcde",
@@ -11,11 +17,42 @@ var testInput = []string{
 		"abcdee",
 		"ababab",
 	}
-
-func TestPartOne(t *testing.T) {
 	expected := 12
-	got := PartOne(testInput)
+	got := PartOne(input)
 	if got != expected {
 		t.Errorf("PartOne() = %d, want %d", got, expected)
 	}
 }
+
+func TestPartTwo(t *testing.T) {
+	input := []string{
+		"abcde",
+		"fghij",
+		"klmno",
+		"pqrst",
+		"fguij",
+		"axcye",
+		"wvxyz",
+	}
+	expected := "fgij"
+
+	oldStdout := os.Stdout
+	r, w, err := os.Pipe()
+	if err != nil {
+		t.Fatalf("Failed to create pipe: %v", err)
+	}
+	os.Stdout = w
+
+	PartTwo(input)
+
+	w.Close()
+	os.Stdout = oldStdout
+
+	var buffer bytes.Buffer
+	buffer.ReadFrom(r)
+	got := strings.TrimSpace(buffer.String())
+
+	if got != expected {
+		t.Errorf("PartTwo() printed %q, want %q", got, expected)
+	}
+}