diff --git a/Makefile b/Makefile
index c65fa7d2..04342dd1 100644
--- a/Makefile
+++ b/Makefile
@@ -38,6 +38,7 @@ fmt:
 fmt-check:
 	@unformatted=$$(gofmt -l $(FMT_PATHS)); [ -z "$$unformatted" ] && exit 0; echo "Unformatted:"; for fn in $$unformatted; do echo "  $$fn"; done; exit 1
 
+
 gen-device: gen-device-avr gen-device-nrf gen-device-sam gen-device-stm32
 
 gen-device-avr:
@@ -85,6 +86,9 @@ build/tinygo:
 test:
 	CGO_CPPFLAGS="$(CGO_CPPFLAGS)" CGO_CXXFLAGS="$(CGO_CXXFLAGS)" CGO_LDFLAGS="$(CGO_LDFLAGS)" go test -v -tags byollvm .
 
+tinygo-test:
+	cd tests/tinygotest && tinygo test
+
 .PHONY: smoketest smoketest-no-avr
 smoketest: smoketest-no-avr
 	tinygo build -size short -o test.elf -target=arduino             examples/blinky1
diff --git a/compiler/compiler.go b/compiler/compiler.go
index 27ee530b..93c3f496 100644
--- a/compiler/compiler.go
+++ b/compiler/compiler.go
@@ -48,6 +48,12 @@ type Config struct {
 	TINYGOROOT    string   // GOROOT for TinyGo
 	GOPATH        string   // GOPATH, like `go env GOPATH`
 	BuildTags     []string // build tags for TinyGo (empty means {Config.GOOS/Config.GOARCH})
+	TestConfig    TestConfig
+}
+
+type TestConfig struct {
+	CompileTestBinary bool
+	// TODO: Filter the test functions to run, include verbose flag, etc
 }
 
 type Compiler struct {
@@ -214,7 +220,7 @@ func (c *Compiler) Compile(mainPath string) []error {
 				path = path[len(tinygoPath+"/src/"):]
 			}
 			switch path {
-			case "machine", "os", "reflect", "runtime", "runtime/volatile", "sync":
+			case "machine", "os", "reflect", "runtime", "runtime/volatile", "sync", "testing":
 				return path
 			default:
 				if strings.HasPrefix(path, "device/") || strings.HasPrefix(path, "examples/") {
@@ -241,6 +247,7 @@ func (c *Compiler) Compile(mainPath string) []error {
 		CFlags:       c.CFlags,
 		ClangHeaders: c.ClangHeaders,
 	}
+
 	if strings.HasSuffix(mainPath, ".go") {
 		_, err = lprogram.ImportFile(mainPath)
 		if err != nil {
@@ -252,12 +259,13 @@ func (c *Compiler) Compile(mainPath string) []error {
 			return []error{err}
 		}
 	}
+
 	_, err = lprogram.Import("runtime", "")
 	if err != nil {
 		return []error{err}
 	}
 
-	err = lprogram.Parse()
+	err = lprogram.Parse(c.TestConfig.CompileTestBinary)
 	if err != nil {
 		return []error{err}
 	}
diff --git a/loader/loader.go b/loader/loader.go
index cfa81e99..1cf37156 100644
--- a/loader/loader.go
+++ b/loader/loader.go
@@ -1,6 +1,7 @@
 package loader
 
 import (
+	"bytes"
 	"errors"
 	"go/ast"
 	"go/build"
@@ -10,12 +11,15 @@ import (
 	"os"
 	"path/filepath"
 	"sort"
+	"strings"
+	"text/template"
 
 	"github.com/tinygo-org/tinygo/cgo"
 )
 
 // Program holds all packages and some metadata about the program as a whole.
 type Program struct {
+	mainPkg      string
 	Build        *build.Context
 	OverlayBuild *build.Context
 	OverlayPath  func(path string) string
@@ -64,6 +68,11 @@ func (p *Program) Import(path, srcDir string) (*Package, error) {
 	p.sorted = nil // invalidate the sorted order of packages
 	pkg := p.newPackage(buildPkg)
 	p.Packages[buildPkg.ImportPath] = pkg
+
+	if p.mainPkg == "" {
+		p.mainPkg = buildPkg.ImportPath
+	}
+
 	return pkg, nil
 }
 
@@ -93,6 +102,11 @@ func (p *Program) ImportFile(path string) (*Package, error) {
 	p.sorted = nil // invalidate the sorted order of packages
 	pkg := p.newPackage(buildPkg)
 	p.Packages[buildPkg.ImportPath] = pkg
+
+	if p.mainPkg == "" {
+		p.mainPkg = buildPkg.ImportPath
+	}
+
 	return pkg, nil
 }
 
@@ -171,10 +185,12 @@ func (p *Program) sort() {
 // The returned error may be an Errors error, which contains a list of errors.
 //
 // Idempotent.
-func (p *Program) Parse() error {
+func (p *Program) Parse(compileTestBinary bool) error {
+	includeTests := compileTestBinary
+
 	// Load all imports
 	for _, pkg := range p.Sorted() {
-		err := pkg.importRecursively()
+		err := pkg.importRecursively(includeTests)
 		if err != nil {
 			if err, ok := err.(*ImportCycleError); ok {
 				if pkg.ImportPath != err.Packages[0] {
@@ -187,7 +203,14 @@ func (p *Program) Parse() error {
 
 	// Parse all packages.
 	for _, pkg := range p.Sorted() {
-		err := pkg.Parse()
+		err := pkg.Parse(includeTests)
+		if err != nil {
+			return err
+		}
+	}
+
+	if compileTestBinary {
+		err := p.SwapTestMain()
 		if err != nil {
 			return err
 		}
@@ -204,6 +227,83 @@ func (p *Program) Parse() error {
 	return nil
 }
 
+func (p *Program) SwapTestMain() error {
+	var tests []string
+
+	isTestFunc := func(f *ast.FuncDecl) bool {
+		// TODO: improve signature check
+		if strings.HasPrefix(f.Name.Name, "Test") && f.Name.Name != "TestMain" {
+			return true
+		}
+		return false
+	}
+	mainPkg := p.Packages[p.mainPkg]
+	for _, f := range mainPkg.Files {
+		for i, d := range f.Decls {
+			switch v := d.(type) {
+			case *ast.FuncDecl:
+				if isTestFunc(v) {
+					tests = append(tests, v.Name.Name)
+				}
+				if v.Name.Name == "main" {
+					// Remove main
+					if len(f.Decls) == 1 {
+						f.Decls = make([]ast.Decl, 0)
+					} else {
+						f.Decls[i] = f.Decls[len(f.Decls)-1]
+						f.Decls = f.Decls[:len(f.Decls)-1]
+					}
+				}
+			}
+		}
+	}
+
+	// TODO: Check if they defined a TestMain and call it instead of testing.TestMain
+	const mainBody = `package main
+
+import (
+	"testing"
+)
+
+func main () {
+	m := &testing.M{
+		Tests: []testing.TestToCall{
+{{range .TestFunctions}}
+			{Name: "{{.}}", Func: {{.}}},
+{{end}}
+		},
+	}
+
+	testing.TestMain(m)
+}
+`
+	tmpl := template.Must(template.New("testmain").Parse(mainBody))
+	b := bytes.Buffer{}
+	tmplData := struct {
+		TestFunctions []string
+	}{
+		TestFunctions: tests,
+	}
+
+	err := tmpl.Execute(&b, tmplData)
+	if err != nil {
+		return err
+	}
+	path := filepath.Join(p.mainPkg, "$testmain.go")
+
+	if p.fset == nil {
+		p.fset = token.NewFileSet()
+	}
+
+	newMain, err := parser.ParseFile(p.fset, path, b.Bytes(), parser.AllErrors)
+	if err != nil {
+		return err
+	}
+	mainPkg.Files = append(mainPkg.Files, newMain)
+
+	return nil
+}
+
 // parseFile is a wrapper around parser.ParseFile.
 func (p *Program) parseFile(path string, mode parser.Mode) (*ast.File, error) {
 	if p.fset == nil {
@@ -228,7 +328,7 @@ func (p *Program) parseFile(path string, mode parser.Mode) (*ast.File, error) {
 // Parse parses and typechecks this package.
 //
 // Idempotent.
-func (p *Package) Parse() error {
+func (p *Package) Parse(includeTests bool) error {
 	if len(p.Files) != 0 {
 		return nil
 	}
@@ -242,7 +342,7 @@ func (p *Package) Parse() error {
 		return nil
 	}
 
-	files, err := p.parseFiles()
+	files, err := p.parseFiles(includeTests)
 	if err != nil {
 		return err
 	}
@@ -281,11 +381,21 @@ func (p *Package) Check() error {
 }
 
 // parseFiles parses the loaded list of files and returns this list.
-func (p *Package) parseFiles() ([]*ast.File, error) {
+func (p *Package) parseFiles(includeTests bool) ([]*ast.File, error) {
 	// TODO: do this concurrently.
 	var files []*ast.File
 	var fileErrs []error
-	for _, file := range p.GoFiles {
+
+	var gofiles []string
+	if includeTests {
+		gofiles = make([]string, 0, len(p.GoFiles)+len(p.TestGoFiles))
+		gofiles = append(gofiles, p.GoFiles...)
+		gofiles = append(gofiles, p.TestGoFiles...)
+	} else {
+		gofiles = p.GoFiles
+	}
+
+	for _, file := range gofiles {
 		f, err := p.parseFile(filepath.Join(p.Package.Dir, file), parser.ParseComments)
 		if err != nil {
 			fileErrs = append(fileErrs, err)
@@ -320,6 +430,7 @@ func (p *Package) parseFiles() ([]*ast.File, error) {
 	if len(fileErrs) != 0 {
 		return nil, Errors{p, fileErrs}
 	}
+
 	return files, nil
 }
 
@@ -340,9 +451,15 @@ func (p *Package) Import(to string) (*types.Package, error) {
 // importRecursively() on the imported packages as well.
 //
 // Idempotent.
-func (p *Package) importRecursively() error {
+func (p *Package) importRecursively(includeTests bool) error {
 	p.Importing = true
-	for _, to := range p.Package.Imports {
+
+	imports := p.Package.Imports
+	if includeTests {
+		imports = append(imports, p.Package.TestImports...)
+	}
+
+	for _, to := range imports {
 		if to == "C" {
 			// Do CGo processing in a later stage.
 			continue
@@ -360,7 +477,7 @@ func (p *Package) importRecursively() error {
 		if importedPkg.Importing {
 			return &ImportCycleError{[]string{p.ImportPath, importedPkg.ImportPath}, p.ImportPos[to]}
 		}
-		err = importedPkg.importRecursively()
+		err = importedPkg.importRecursively(false)
 		if err != nil {
 			if err, ok := err.(*ImportCycleError); ok {
 				err.Packages = append([]string{p.ImportPath}, err.Packages...)
diff --git a/main.go b/main.go
index 4eaa359c..97ea47d3 100644
--- a/main.go
+++ b/main.go
@@ -54,6 +54,7 @@ type BuildConfig struct {
 	cFlags        []string
 	ldFlags       []string
 	wasmAbi       string
+	testConfig    compiler.TestConfig
 }
 
 // Helper function for Compiler object.
@@ -108,6 +109,7 @@ func Compile(pkgName, outpath string, spec *TargetSpec, config *BuildConfig, act
 		GOROOT:        goroot,
 		GOPATH:        getGopath(),
 		BuildTags:     tags,
+		TestConfig:    config.testConfig,
 	}
 	c, err := compiler.NewCompiler(pkgName, compilerConfig)
 	if err != nil {
@@ -349,6 +351,30 @@ func Build(pkgName, outpath, target string, config *BuildConfig) error {
 	})
 }
 
+func Test(pkgName, target string, config *BuildConfig) error {
+	spec, err := LoadTarget(target)
+	if err != nil {
+		return err
+	}
+
+	spec.BuildTags = append(spec.BuildTags, "test")
+	config.testConfig.CompileTestBinary = true
+	return Compile(pkgName, ".elf", spec, config, func(tmppath string) error {
+		cmd := exec.Command(tmppath)
+		cmd.Stdout = os.Stdout
+		cmd.Stderr = os.Stderr
+		err := cmd.Run()
+		if err != nil {
+			// Propagate the exit code
+			if err, ok := err.(*exec.ExitError); ok {
+				os.Exit(err.ExitCode())
+			}
+			return &commandError{"failed to run compiled binary", tmppath, err}
+		}
+		return nil
+	})
+}
+
 func Flash(pkgName, target, port string, config *BuildConfig) error {
 	spec, err := LoadTarget(target)
 	if err != nil {
@@ -656,6 +682,13 @@ func main() {
 		}
 		err := Run(flag.Arg(0), *target, config)
 		handleCompilerError(err)
+	case "test":
+		pkgRoot := "."
+		if flag.NArg() == 1 {
+			pkgRoot = flag.Arg(0)
+		}
+		err := Test(pkgRoot, *target, config)
+		handleCompilerError(err)
 	case "clean":
 		// remove cache directory
 		dir := cacheDir()
diff --git a/src/reflect/value.go b/src/reflect/value.go
index 51128b81..577a944b 100644
--- a/src/reflect/value.go
+++ b/src/reflect/value.go
@@ -92,7 +92,7 @@ func (v Value) Pointer() uintptr {
 }
 
 func (v Value) IsValid() bool {
-	panic("unimplemented: (reflect.Value).IsValid()")
+	return v.typecode != 0
 }
 
 func (v Value) CanInterface() bool {
diff --git a/src/testing/doc.go b/src/testing/doc.go
new file mode 100644
index 00000000..b5026d80
--- /dev/null
+++ b/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.
+*/
diff --git a/src/testing/testing.go b/src/testing/testing.go
new file mode 100644
index 00000000..1d7ea051
--- /dev/null
+++ b/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
+}
diff --git a/tests/tinygotest/main.go b/tests/tinygotest/main.go
new file mode 100644
index 00000000..84ed9700
--- /dev/null
+++ b/tests/tinygotest/main.go
@@ -0,0 +1,14 @@
+package main
+
+import (
+	"fmt"
+)
+
+func main() {
+	Thing()
+	fmt.Println("normal main")
+}
+
+func Thing() {
+	fmt.Println("THING")
+}
diff --git a/tests/tinygotest/main_test.go b/tests/tinygotest/main_test.go
new file mode 100644
index 00000000..61ce2828
--- /dev/null
+++ b/tests/tinygotest/main_test.go
@@ -0,0 +1,16 @@
+package main
+
+import (
+	"testing" // This is the tinygo testing package
+)
+
+func TestFail1(t *testing.T) {
+	t.Error("TestFail1 failed because of stuff and things")
+}
+
+func TestFail2(t *testing.T) {
+	t.Error("TestFail2 failed for reasons")
+}
+
+func TestPass(t *testing.T) {
+}