all: fix some vet-caught formatting errors, mostly but not only in tests

Could go in 1.5, although not critical.
See also #12107

Change-Id: I7f1608b58581d21df4db58f0db654fef79e33a90
Reviewed-on: https://go-review.googlesource.com/13481
Reviewed-by: Dave Cheney <dave@cheney.net>
diff --git a/src/cmd/internal/rsc.io/arm/armasm/ext_test.go b/src/cmd/internal/rsc.io/arm/armasm/ext_test.go
index aa87cf9..429fd88 100644
--- a/src/cmd/internal/rsc.io/arm/armasm/ext_test.go
+++ b/src/cmd/internal/rsc.io/arm/armasm/ext_test.go
@@ -178,7 +178,7 @@
 	t.Logf("%d test cases, %d expected mismatches, %d failures; %.0f cases/second", totalTests, totalSkips, totalErrors, float64(totalTests)/time.Since(start).Seconds())
 
 	if err := <-errc; err != nil {
-		t.Fatal("external disassembler: %v", err)
+		t.Fatalf("external disassembler: %v", err)
 	}
 
 }
diff --git a/src/cmd/internal/rsc.io/x86/x86asm/ext_test.go b/src/cmd/internal/rsc.io/x86/x86asm/ext_test.go
index bb56c0d..35ac3cf 100644
--- a/src/cmd/internal/rsc.io/x86/x86asm/ext_test.go
+++ b/src/cmd/internal/rsc.io/x86/x86asm/ext_test.go
@@ -177,7 +177,7 @@
 	t.Logf("%d test cases, %d expected mismatches, %d failures; %.0f cases/second", totalTests, totalSkips, totalErrors, float64(totalTests)/time.Since(start).Seconds())
 
 	if err := <-errc; err != nil {
-		t.Fatal("external disassembler: %v", err)
+		t.Fatalf("external disassembler: %v", err)
 	}
 
 }
diff --git a/src/crypto/ecdsa/ecdsa_test.go b/src/crypto/ecdsa/ecdsa_test.go
index 169944d..2bd31b8 100644
--- a/src/crypto/ecdsa/ecdsa_test.go
+++ b/src/crypto/ecdsa/ecdsa_test.go
@@ -91,11 +91,11 @@
 
 	if s0.Cmp(s1) == 0 {
 		// This should never happen.
-		t.Errorf("%s: the signatures on two different messages were the same")
+		t.Errorf("%s: the signatures on two different messages were the same", tag)
 	}
 
 	if r0.Cmp(r1) == 0 {
-		t.Errorf("%s: the nonce used for two diferent messages was the same")
+		t.Errorf("%s: the nonce used for two diferent messages was the same", tag)
 	}
 }
 
@@ -126,11 +126,11 @@
 	}
 
 	if s0.Cmp(s1) == 0 {
-		t.Errorf("%s: two signatures of the same message produced the same result")
+		t.Errorf("%s: two signatures of the same message produced the same result", tag)
 	}
 
 	if r0.Cmp(r1) == 0 {
-		t.Errorf("%s: two signatures of the same message produced the same nonce")
+		t.Errorf("%s: two signatures of the same message produced the same nonce", tag)
 	}
 }
 
diff --git a/src/crypto/rsa/pkcs1v15_test.go b/src/crypto/rsa/pkcs1v15_test.go
index 8925375..47444f3 100644
--- a/src/crypto/rsa/pkcs1v15_test.go
+++ b/src/crypto/rsa/pkcs1v15_test.go
@@ -160,7 +160,7 @@
 		}
 
 		if test.out != "FAIL" && !bytes.Equal(plaintext, []byte(test.out)) {
-			t.Errorf("#%d: incorrect plaintext: got %x, want %x", plaintext, test.out)
+			t.Errorf("#%d: incorrect plaintext: got %x, want %x", i, plaintext, test.out)
 		}
 	}
 }
diff --git a/src/crypto/tls/handshake_server_test.go b/src/crypto/tls/handshake_server_test.go
index 20c2bd6..438fb31 100644
--- a/src/crypto/tls/handshake_server_test.go
+++ b/src/crypto/tls/handshake_server_test.go
@@ -84,7 +84,7 @@
 	s.Close()
 	if len(expectedSubStr) == 0 {
 		if err != nil && err != io.EOF {
-			t.Errorf("Got error: %s; expected to succeed", err, expectedSubStr)
+			t.Errorf("Got error: %s; expected to succeed", err)
 		}
 	} else if err == nil || !strings.Contains(err.Error(), expectedSubStr) {
 		t.Errorf("Got error: %s; expected to match substring '%s'", err, expectedSubStr)
diff --git a/src/encoding/gob/codec_test.go b/src/encoding/gob/codec_test.go
index c2583bf..18327a6 100644
--- a/src/encoding/gob/codec_test.go
+++ b/src/encoding/gob/codec_test.go
@@ -1488,7 +1488,7 @@
 		var foo struct{}
 		err := d.Decode(&foo)
 		if err != errBadType {
-			t.Fatal("decode: expected %s, got %s", errBadType, err)
+			t.Fatalf("decode: expected %s, got %s", errBadType, err)
 		}
 	}
 }
diff --git a/src/internal/trace/parser_test.go b/src/internal/trace/parser_test.go
index 0eeb3e6..fecefc4 100644
--- a/src/internal/trace/parser_test.go
+++ b/src/internal/trace/parser_test.go
@@ -24,7 +24,7 @@
 	for _, data := range tests {
 		events, err := Parse(strings.NewReader(data))
 		if err == nil || events != nil {
-			t.Fatalf("no error on input: %q\n", t)
+			t.Fatalf("no error on input: %q\n", data)
 		}
 	}
 }
diff --git a/src/net/http/transport_test.go b/src/net/http/transport_test.go
index c21d4af..cc19342 100644
--- a/src/net/http/transport_test.go
+++ b/src/net/http/transport_test.go
@@ -2645,7 +2645,7 @@
 		req.Header.Set("User-Agent", "x") // known value for test
 		res, err := tr.RoundTrip(req)
 		if err != nil {
-			t.Error("RoundTrip: %v", err)
+			t.Errorf("RoundTrip: %v", err)
 			close(resc)
 			return
 		}
diff --git a/src/path/filepath/path_test.go b/src/path/filepath/path_test.go
index 1c32e27..153a398 100644
--- a/src/path/filepath/path_test.go
+++ b/src/path/filepath/path_test.go
@@ -402,18 +402,18 @@
 func chtmpdir(t *testing.T) (restore func()) {
 	oldwd, err := os.Getwd()
 	if err != nil {
-		t.Fatal("chtmpdir: %v", err)
+		t.Fatalf("chtmpdir: %v", err)
 	}
 	d, err := ioutil.TempDir("", "test")
 	if err != nil {
-		t.Fatal("chtmpdir: %v", err)
+		t.Fatalf("chtmpdir: %v", err)
 	}
 	if err := os.Chdir(d); err != nil {
-		t.Fatal("chtmpdir: %v", err)
+		t.Fatalf("chtmpdir: %v", err)
 	}
 	return func() {
 		if err := os.Chdir(oldwd); err != nil {
-			t.Fatal("chtmpdir: %v", err)
+			t.Fatalf("chtmpdir: %v", err)
 		}
 		os.RemoveAll(d)
 	}