google: fix warnings from go vet

go vet reports the following warnings:
google/jwt_test.go:85:
missing argument for Fatalf("%q"): format reads arg 2, have only 1 args

google/sdk_test.go:28:
wrong number of args for format in Errorf call: 1 needed but 2 args

Change-Id: If5acfae42b558ced7694dd7bc6f12ab4a3cb6115
Reviewed-on: https://go-review.googlesource.com/24992
Reviewed-by: Jaana Burcu Dogan <jbd@google.com>

google/jwt_test.go

@@ -82,7 +82,7 @@ func TestJWTAccessTokenSourceFromJSON(t *testing.T) {
 	}
 	var hdr jws.Header
 	if err := json.Unmarshal([]byte(hdrJSON), &hdr); err != nil {
-		t.Fatalf("json.Unmarshal: %v (%q)", err)
+		t.Fatalf("json.Unmarshal: %v (%q)", err, hdrJSON)
 	}
 
 	if got, want := hdr.KeyID, "268f54e43a1af97cfc71731688434f45aca15c8b"; got != want {

google/sdk_test.go

@@ -25,9 +25,9 @@ func TestSDKConfig(t *testing.T) {
 		c, err := NewSDKConfig(tt.account)
 		if got, want := err != nil, tt.err; got != want {
 			if !tt.err {
-				t.Errorf("expected no error, got error: %v", tt.err, err)
+				t.Errorf("got %v, want nil", err)
 			} else {
-				t.Errorf("expected error, got none")
+				t.Errorf("got nil, want error")
 			}
 			continue
 		}
@@ -36,11 +36,11 @@ func TestSDKConfig(t *testing.T) {
 		}
 		tok := c.initialToken
 		if tok == nil {
-			t.Errorf("expected token %q, got: nil", tt.accessToken)
+			t.Errorf("got nil, want %q", tt.accessToken)
 			continue
 		}
 		if tok.AccessToken != tt.accessToken {
-			t.Errorf("expected token %q, got: %q", tt.accessToken, tok.AccessToken)
+			t.Errorf("got %q, want %q", tok.AccessToken, tt.accessToken)
 		}
 	}
 }