Fix color leakage (#10)

Only colorizing output that indicates test result status. This includes
"ok", "PASS", etc. The fix prevents that coloration from remaining set
and colorizing error and logging output that doesn't directly indicate
whether a test passed or failed. For example, a line like
"some/package/file.go:20:10: something went wrong" won't be colorized.

main.go

@@ -21,9 +21,9 @@ import (
 )
 
 var (
-	success = color.New(color.FgGreen)
-	skipped = color.New(color.FgYellow)
-	fail    = color.New(color.FgHiRed)
+	success = color.FgGreen
+	skipped = color.FgYellow
+	fail = color.FgHiRed
 )
 
 const paletteEnv = "GOTEST_PALETTE"
@@ -75,41 +75,31 @@ func consume(wg *sync.WaitGroup, r io.Reader) {
 	}
 }
 
-var c *color.Color
-
 func parse(line string) {
 	trimmed := strings.TrimSpace(line)
+	defer color.Unset()
 
 	switch {
-	case strings.HasPrefix(trimmed, "=== RUN"):
-		fallthrough
-	case strings.HasPrefix(trimmed, "?"):
-		c = nil
-
 	// success
 	case strings.HasPrefix(trimmed, "--- PASS"):
 		fallthrough
 	case strings.HasPrefix(trimmed, "ok"):
 		fallthrough
 	case strings.HasPrefix(trimmed, "PASS"):
-		c = success
+		color.Set(success)
 
 	// skipped
 	case strings.HasPrefix(trimmed, "--- SKIP"):
-		c = skipped
+		color.Set(skipped)
 
 	// failure
 	case strings.HasPrefix(trimmed, "--- FAIL"):
 		fallthrough
 	case strings.HasPrefix(trimmed, "FAIL"):
-		c = fail
+		color.Set(fail)
 	}
 
-	if c == nil {
-		fmt.Printf("%s\n", line)
-		return
-	}
-	c.Printf("%s\n", line)
+	fmt.Printf("%s\n", line)
 }
 
 func enableOnCI() {
@@ -138,10 +128,10 @@ func setPalette() {
 		return
 	}
 	if c, ok := colors[vals[0]]; ok {
-		fail = color.New(c)
+		fail = c
 	}
 	if c, ok := colors[vals[1]]; ok {
-		success = color.New(c)
+		success = c
 	}
 }