main: add tests

Add testing infrastructure and one initial test (for
src/runtime/print.go). More tests to be added later.

main_test.go

@@ -0,0 +1,91 @@
+package main
+
+// This file tests the compiler by running Go files in testdata/*.go and
+// comparing their output with the expected output in testdata/*.txt.
+
+import (
+	"bufio"
+	"bytes"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"testing"
+)
+
+const TESTDATA = "testdata"
+
+func TestCompiler(t *testing.T) {
+	matches, err := filepath.Glob(TESTDATA + "/*.go")
+	if err != nil {
+		t.Fatal("could not read test files:", err)
+	}
+	if len(matches) == 0 {
+		t.Fatal("no test files found")
+	}
+
+	// Create a temporary directory for test output files.
+	tmpdir, err := ioutil.TempDir("", "tinygo-test")
+	if err != nil {
+		t.Fatal("could not create temporary directory:", err)
+	}
+	defer os.RemoveAll(tmpdir)
+
+	for _, path := range matches {
+		t.Run(path, func(t *testing.T) {
+			runTest(path, tmpdir, t)
+		})
+	}
+}
+
+func runTest(path, tmpdir string, t *testing.T) {
+	// Get the expected output for this test.
+	txtpath := path[:len(path)-3] + ".txt"
+	f, err := os.Open(txtpath)
+	if err != nil {
+		t.Fatal("could not open expected output file:", err)
+	}
+	expected, err := ioutil.ReadAll(f)
+	if err != nil {
+		t.Fatal("could not read expected output file:", err)
+	}
+
+	// Build the test binary.
+	binary := filepath.Join(tmpdir, "test")
+	err = Build(path, binary, "", false, false, "")
+	if err != nil {
+		t.Log("failed to build:", err)
+		t.Fail()
+	}
+
+	// Run the test.
+	cmd := exec.Command(binary)
+	stdout := &bytes.Buffer{}
+	cmd.Stdout = stdout
+	err = cmd.Run()
+
+	// putchar() prints CRLF, convert it to LF.
+	actual := bytes.Replace(stdout.Bytes(), []byte{'\r', '\n'}, []byte{'\n'}, -1)
+
+	// Check whether the command ran successfully.
+	fail := false
+	if err != nil {
+		t.Log("failed to run:", err)
+		fail = true
+	} else if !bytes.Equal(expected, actual) {
+		t.Log("output did not match")
+		fail = true
+	}
+
+	if fail {
+		r := bufio.NewReader(bytes.NewReader(actual))
+		for {
+			line, err := r.ReadString('\n')
+			if err != nil {
+				break
+			}
+			t.Log("stdout:", line[:len(line)-1])
+		}
+		t.Fail()
+	}
+}