mtest: implement NewCtx and Run, and use them in mnet and mhttp's tests

mhttp/mhttp_test.go

@@ -8,28 +8,18 @@ import (
 	"net/http/httptest"
 	. "testing"
 
-	"github.com/mediocregopher/mediocre-go-lib/mctx"
-	"github.com/mediocregopher/mediocre-go-lib/mlog"
-	"github.com/mediocregopher/mediocre-go-lib/mrun"
+	"github.com/mediocregopher/mediocre-go-lib/mtest"
 	"github.com/mediocregopher/mediocre-go-lib/mtest/massert"
 )
 
 func TestMListenAndServe(t *T) {
-	// TODO mtest.NewCtx
-	ctx := mctx.ChildOf(mctx.New(), "test")
-	logger := mlog.From(ctx)
-	logger.SetMaxLevel(mlog.DebugLevel)
-	mlog.CtxSet(ctx, logger)
+	ctx := mtest.NewCtx()
 
-	h := http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
+	srv := MListenAndServe(ctx, http.HandlerFunc(func(rw http.ResponseWriter, r *http.Request) {
 		io.Copy(rw, r.Body)
-	})
-
-	srv := MListenAndServe(ctx, h)
-	if err := mrun.Start(ctx); err != nil {
-		t.Fatal(err)
-	}
+	}))
 
+	mtest.Run(ctx, t, func() {
 		body := bytes.NewBufferString("HELLO")
 		resp, err := http.Post("http://"+srv.Addr, "text/plain", body)
 		if err != nil {
@@ -43,10 +33,7 @@ func TestMListenAndServe(t *T) {
 		} else if string(respBody) != "HELLO" {
 			t.Fatalf("unexpected respBody: %q", respBody)
 		}
-
-	if err := mrun.Stop(ctx); err != nil {
-		t.Fatal(err)
-	}
+	})
 }
 
 func TestAddXForwardedFor(t *T) {

mnet/mnet_test.go

@@ -6,10 +6,7 @@ import (
 	"net"
 	. "testing"
 
-	"github.com/mediocregopher/mediocre-go-lib/mcfg"
-	"github.com/mediocregopher/mediocre-go-lib/mctx"
-	"github.com/mediocregopher/mediocre-go-lib/mlog"
-	"github.com/mediocregopher/mediocre-go-lib/mrun"
+	"github.com/mediocregopher/mediocre-go-lib/mtest"
 	"github.com/mediocregopher/mediocre-go-lib/mtest/massert"
 )
 
@@ -39,19 +36,9 @@ func TestIsReservedIP(t *T) {
 }
 
 func TestMListen(t *T) {
-	// TODO mtest.NewCtx
-	ctx := mctx.ChildOf(mctx.New(), "test")
-	logger := mlog.From(ctx)
-	logger.SetMaxLevel(mlog.DebugLevel)
-	mlog.CtxSet(ctx, logger)
-
+	ctx := mtest.NewCtx()
 	l := MListen(ctx, "", "")
-	if err := mcfg.Populate(ctx, nil); err != nil {
-		t.Fatal(err)
-	} else if err := mrun.Start(ctx); err != nil {
-		t.Fatal(err)
-	}
-
+	mtest.Run(ctx, t, func() {
 		go func() {
 			conn, err := net.Dial("tcp", l.Addr().String())
 			if err != nil {
@@ -70,8 +57,5 @@ func TestMListen(t *T) {
 		} else if string(b) != "hello world" {
 			t.Fatalf("read %q from conn", b)
 		}
-
-	if err := mrun.Stop(ctx); err != nil {
-		t.Fatal(err)
-	}
+	})
 }

mtest/mtest.go

@@ -1,2 +1,66 @@
 // Package mtest implements functionality useful for testing.
 package mtest
+
+import (
+	"testing"
+
+	"github.com/mediocregopher/mediocre-go-lib/mcfg"
+	"github.com/mediocregopher/mediocre-go-lib/mctx"
+	"github.com/mediocregopher/mediocre-go-lib/mlog"
+	"github.com/mediocregopher/mediocre-go-lib/mrun"
+)
+
+type ctxKey int
+
+// NewCtx creates and returns a root Context suitable for testing.
+func NewCtx() mctx.Context {
+	ctx := mctx.New()
+	mlog.From(ctx).SetMaxLevel(mlog.DebugLevel)
+	return ctx
+}
+
+// SetEnv sets the given environment variable on the given Context, such that it
+// will be used as if it was a real environment variable when the Run function
+// from this package is called.
+func SetEnv(ctx mctx.Context, key, val string) {
+	mctx.GetSetMutableValue(ctx, false, ctxKey(0), func(i interface{}) interface{} {
+		m, _ := i.(map[string]string)
+		if m == nil {
+			m = map[string]string{}
+		}
+		m[key] = val
+		return m
+	})
+}
+
+// Run performs the following using the given Context:
+//
+// - Calls mcfg.Populate using any variables set by SetEnv.
+//
+// - Calls mrun.Start
+//
+// - Calls the passed in body callback.
+//
+// - Calls mrun.Stop
+//
+// The intention is that Run is used within a test on a Context created via
+// NewCtx, after any setup functions have been called (e.g. mnet.MListen).
+func Run(ctx mctx.Context, t *testing.T, body func()) {
+	envMap, _ := mctx.MutableValue(ctx, ctxKey(0)).(map[string]string)
+	env := make([]string, 0, len(envMap))
+	for key, val := range envMap {
+		env = append(env, key+"="+val)
+	}
+
+	if err := mcfg.Populate(ctx, mcfg.SourceEnv{Env: env}); err != nil {
+		t.Fatal(err)
+	} else if err := mrun.Start(ctx); err != nil {
+		t.Fatal(err)
+	}
+
+	body()
+
+	if err := mrun.Stop(ctx); err != nil {
+		t.Fatal(err)
+	}
+}

mtest/mtest_test.go

@@ -0,0 +1,18 @@
+package mtest
+
+import (
+	. "testing"
+
+	"github.com/mediocregopher/mediocre-go-lib/mcfg"
+)
+
+func TestRun(t *T) {
+	ctx := NewCtx()
+	arg := mcfg.RequiredString(ctx, "arg", "Required by this test")
+	SetEnv(ctx, "ARG", "foo")
+	Run(ctx, t, func() {
+		if *arg != "foo" {
+			t.Fatalf(`arg not set to "foo", is set to %q`, *arg)
+		}
+	})
+}