google: clean up tests and add godoc comments

Change-Id: I54d2702a149d1eccd64f8ef2ed4b4617429c9358

google/internal/externalaccount/sts_exchange.go

@@ -16,6 +16,10 @@ import (
 	"strings"
 )
 
+// ExchangeToken preforms a oauth2 token exchange with the provided endpoint.
+// The first 4 fields are all mandatory.  headers can be used to pass additional
+// headers beyond the bare minimum required by the token exchange.  options can
+// be used to pass additional JSON-structured options to the remote server.
 func ExchangeToken(ctx context.Context, endpoint string, request *STSTokenExchangeRequest, authentication ClientAuthentication, headers http.Header, options map[string]interface{}) (*STSTokenExchangeResponse, error) {
 
 	client := oauth2.NewClient(ctx, nil)
@@ -63,9 +67,11 @@ func ExchangeToken(ctx context.Context, endpoint string, request *STSTokenExchan
 
 	}
 
+
 	return &stsResp, nil
 }
 
+// STSTokenExchangeRequest contains fields necessary to make an oauth2 token exchange.
 type STSTokenExchangeRequest struct {
 	ActingParty struct {
 		ActorToken     string
@@ -80,6 +86,7 @@ type STSTokenExchangeRequest struct {
 	SubjectTokenType   string
 }
 
+// STSTokenExchangeResponse is used to decode the remote server's response during an oauth2 token exchange.
 type STSTokenExchangeResponse struct {
 	AccessToken     string `json:"access_token"`
 	IssuedTokenType string `json:"issued_token_type"`

google/internal/externalaccount/sts_exchange_test.go

@@ -47,7 +47,6 @@ var expectedToken = STSTokenExchangeResponse{
 }
 
 func TestExchangeToken(t *testing.T) {
-
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		if r.Method != "POST" {
 			t.Errorf("Unexpected request method, %v is found", r.Method)
@@ -55,24 +54,23 @@ func TestExchangeToken(t *testing.T) {
 		if r.URL.String() != "/" {
 			t.Errorf("Unexpected request URL, %v is found", r.URL)
 		}
-		headerAuth := r.Header.Get("Authorization")
+		if got, want := r.Header.Get("Authorization"), "Basic cmJyZ25vZ25yaG9uZ28zYmk0Z2I5Z2hnOWc6bm90c29zZWNyZXQ="; got != want {
-		if headerAuth != "Basic cmJyZ25vZ25yaG9uZ28zYmk0Z2I5Z2hnOWc6bm90c29zZWNyZXQ=" {
+			t.Errorf("Unexpected authorization header, got %v, want %v", got, want)
-			t.Errorf("Unexpected autohrization header, %v is found", headerAuth)
 		}
-		headerContentType := r.Header.Get("Content-Type")
+		if got, want := r.Header.Get("Content-Type"), "application/x-www-form-urlencoded"; got != want{
-		if headerContentType != "application/x-www-form-urlencoded" {
+			t.Errorf("Unexpected Content-Type header, got %v, want %v", got, want)
-			t.Errorf("Unexpected Content-Type header, %v is found", headerContentType)
 		}
 		body, err := ioutil.ReadAll(r.Body)
 		if err != nil {
 			t.Errorf("Failed reading request body: %v.", err)
 		}
-		if string(body) != requestbody {
+		if got, want := string(body), requestbody; got != want {
-			t.Errorf("Unexpected exchange payload, %v is found", string(body))
+			t.Errorf("Unexpected exchange payload, got %v but want %v", got, want)
 		}
 		w.Header().Set("Content-Type", "application/json")
 		w.Write([]byte(responseBody))
 	}))
+	defer ts.Close()
 
 	headers := http.Header{}
 	headers.Add("Content-Type", "application/x-www-form-urlencoded")
@@ -95,6 +93,7 @@ func TestExchangeToken_Err(t *testing.T) {
 		w.Header().Set("Content-Type", "application/json")
 		w.Write([]byte("what's wrong with this response?"))
 	}))
+	defer ts.Close()
 
 	headers := http.Header{}
 	headers.Add("Content-Type", "application/x-www-form-urlencoded")
@@ -113,7 +112,7 @@ func TestExchangeToken_Opts(t *testing.T) {
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		body, err := ioutil.ReadAll(r.Body)
 		if err != nil {
-			t.Errorf("Failed reading request body: %v.", err)
+			t.Fatalf("Failed reading request body: %v.", err)
 		}
 		data, err := url.ParseQuery(string(body))
 		if err != nil {
@@ -128,7 +127,7 @@ func TestExchangeToken_Opts(t *testing.T) {
 		var opts map[string]interface{}
 		err = json.Unmarshal([]byte(strOpts[0]), &opts)
 		if len(opts) < 2 {
-			t.Errorf("Too few options recieved.")
+			t.Errorf("Too few options received.")
 		}
 
 		val, ok := opts["one"]
@@ -139,11 +138,11 @@ func TestExchangeToken_Opts(t *testing.T) {
 			if !ok {
 				t.Errorf("Failed to assert the first option parameter as type testOpts.")
 			} else {
-				if tOpts1["first"].(string) != optsValues[0][0] {
+				if got, want := tOpts1["first"].(string), optsValues[0][0]; got != want {
-					t.Errorf("First value in first options field is incorrect; want %v but got %v", tOpts1["first"].(string), optsValues[0][0])
+					t.Errorf("First value in first options field is incorrect; got %v but want %v", got, want)
 				}
-				if tOpts1["second"].(string) != optsValues[0][1] {
+				if got, want := tOpts1["second"].(string), optsValues[0][1]; got != want {
-					t.Errorf("Second value in first options field is incorrect; want %v but got %v", tOpts1["second"].(string), optsValues[0][1])
+					t.Errorf("Second value in first options field is incorrect; got %v but want %v", got, want)
 				}
 			}
 		}
@@ -156,11 +155,11 @@ func TestExchangeToken_Opts(t *testing.T) {
 			if !ok {
 				t.Errorf("Failed to assert the second option parameter as type testOpts.")
 			} else {
-				if tOpts2["first"].(string) != optsValues[1][0] {
+				if got, want := tOpts2["first"].(string), optsValues[1][0]; got != want {
-					t.Errorf("First value in second options field is incorrect; want %v but got %v", tOpts2["first"].(string), optsValues[1][0])
+					t.Errorf("First value in second options field is incorrect; got %v but want %v", got, want)
 				}
-				if tOpts2["second"].(string) != optsValues[1][1] {
+				if got, want := tOpts2["second"].(string), optsValues[1][1]; got != want {
-					t.Errorf("Second value in second options field is incorrect; want %v but got %v", tOpts2["second"].(string), optsValues[1][1])
+					t.Errorf("Second value in second options field is incorrect; got %v but want %v", got, want)
 				}
 			}
 		}
@@ -170,6 +169,7 @@ func TestExchangeToken_Opts(t *testing.T) {
 		w.Write([]byte(responseBody))
 
 	}))
+	defer ts.Close()
 	headers := http.Header{}
 	headers.Add("Content-Type", "application/x-www-form-urlencoded")