Add test command to tinygo (#243)

* Add test command to tinygo

src/testing/doc.go

@@ -0,0 +1,6 @@
+package testing
+
+/*
+ This is a sad stub of the upstream testing package because it doesn't compile
+ with tinygo right now.
+*/

src/testing/testing.go

@@ -0,0 +1,77 @@
+package testing
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"os"
+)
+
+// T is a test helper.
+type T struct {
+	name   string
+	output io.Writer
+
+	// flags the test as having failed when non-zero
+	failed int
+}
+
+// TestToCall is a reference to a test that should be called during a test suite run.
+type TestToCall struct {
+	// Name of the test to call.
+	Name string
+	// Function reference to the test.
+	Func func(*T)
+}
+
+// M is a test suite.
+type M struct {
+	// tests is a list of the test names to execute
+	Tests []TestToCall
+}
+
+// Run the test suite.
+func (m *M) Run() int {
+	failures := 0
+	for _, test := range m.Tests {
+		t := &T{
+			name:   test.Name,
+			output: &bytes.Buffer{},
+		}
+
+		fmt.Printf("=== RUN   %s\n", test.Name)
+		test.Func(t)
+
+		if t.failed == 0 {
+			fmt.Printf("--- PASS: %s\n", test.Name)
+		} else {
+			fmt.Printf("--- FAIL: %s\n", test.Name)
+		}
+		fmt.Println(t.output)
+
+		failures += t.failed
+	}
+
+	if failures > 0 {
+		fmt.Printf("exit status %d\n", failures)
+		fmt.Println("FAIL")
+	}
+	return failures
+}
+
+func TestMain(m *M) {
+	os.Exit(m.Run())
+}
+
+// Error is equivalent to Log followed by Fail
+func (t *T) Error(args ...interface{}) {
+	// This doesn't print the same as in upstream go, but works good enough
+	// TODO: buffer test output like go does
+	fmt.Fprintf(t.output, "\t")
+	fmt.Fprintln(t.output, args...)
+	t.Fail()
+}
+
+func (t *T) Fail() {
+	t.failed = 1
+}