cmd/go: another attempt at flag handling for coverage

The -cover flag is now just enable/disable and is implied if
either of the other flags is set.

R=rsc
CC=golang-dev
https://golang.org/cl/10420043

src/cmd/go/doc.go

@@ -739,24 +739,24 @@ control the execution of any test:
 	    are recorded, equivalent to -test.blockprofilerate=1.
 
 	-cover
-	    Enable basic coverage analysis; shorthand for -covermode=set.
+	    Enable coverage analysis.
 	    TODO: This feature is not yet fully implemented.
 
 	-covermode set,count,atomic
 	    Set the mode for coverage analysis for the package[s]
-	    being tested. The default is to do none, but if -cover or
-	    -coverprofile is specified, coverage is enabled in "set"
-	    mode unless this flag is also specified.
+	    being tested. The default is "set".
 	    The values:
 		set: bool: does this statement run?
 		count: int: how many times does this statement run?
 		atomic: int: count, but correct in multithreaded tests;
 			significantly more expensive.
+	    Implies -cover.
 	    Sets -v. TODO: This will change.
 
 	-coverprofile cover.out
 	    Write a coverage profile to the specified file after all tests
 	    have passed.
+	    Implies -cover.
 
 	-cpu 1,2,4
 	    Specify a list of GOMAXPROCS values for which the tests or

src/cmd/go/test.go

@@ -125,24 +125,24 @@ control the execution of any test:
 	    are recorded, equivalent to -test.blockprofilerate=1.
 
 	-cover
-	    Enable basic coverage analysis; shorthand for -covermode=set.
+	    Enable coverage analysis.
 	    TODO: This feature is not yet fully implemented.
 
 	-covermode set,count,atomic
 	    Set the mode for coverage analysis for the package[s]
-	    being tested. The default is to do none, but if -cover or
-	    -coverprofile is specified, coverage is enabled in "set"
-	    mode unless this flag is also specified.
+	    being tested. The default is "set".
 	    The values:
 		set: bool: does this statement run?
 		count: int: how many times does this statement run?
 		atomic: int: count, but correct in multithreaded tests;
 			significantly more expensive.
+	    Implies -cover.
 	    Sets -v. TODO: This will change.
 
 	-coverprofile cover.out
 	    Write a coverage profile to the specified file after all tests
 	    have passed.
+	    Implies -cover.
 
 	-cpu 1,2,4
 	    Specify a list of GOMAXPROCS values for which the tests or

src/cmd/go/testflag.go

@@ -27,9 +27,9 @@ var usageMessage = `Usage of go test:
   -bench="": passes -test.bench to test
   -benchmem=false: print memory allocation statistics for benchmarks
   -benchtime=1s: passes -test.benchtime to test
-  -cover=false: basic coverage; equivalent to -covermode=set
-  -covermode="": passes -test.covermode to test
-  -coverprofile="": passes -test.coverprofile to test
+  -cover=false: enable coverage analysis
+  -covermode="set": passes -test.covermode to test if -cover
+  -coverprofile="": passes -test.coverprofile to test if -cover
   -cpu="": passes -test.cpu to test
   -cpuprofile="": passes -test.cpuprofile to test
   -memprofile="": passes -test.memprofile to test
@@ -85,7 +85,7 @@ var testFlagDefn = []*testFlagSpec{
 	{name: "bench", passToTest: true},
 	{name: "benchmem", boolVar: new(bool), passToTest: true},
 	{name: "benchtime", passToTest: true},
-	{name: "covermode"}, // Passed to test by special arrangement.
+	{name: "covermode"},
 	{name: "coverprofile", passToTest: true},
 	{name: "cpu", passToTest: true},
 	{name: "cpuprofile", passToTest: true},
@@ -179,12 +179,18 @@ func testFlags(args []string) (packageNames, passToTest []string) {
 		case "blockprofile", "cpuprofile", "memprofile":
 			testProfile = true
 		case "coverprofile":
-			passToTest = setCoverMode("set", passToTest)
+			testCover = true
 			testProfile = true
+		case "covermode":
+			switch value {
+			case "set", "count", "atomic":
+				testCoverMode = value
+			default:
+				fatalf("invalid flag argument for -cover: %q", value)
+			}
+			testCover = true
 		case "outputdir":
 			outputDir = value
-		case "covermode":
-			passToTest = setCoverMode(value, passToTest)
 		}
 		if extraWord {
 			i++
@@ -193,9 +199,11 @@ func testFlags(args []string) (packageNames, passToTest []string) {
 			passToTest = append(passToTest, "-test."+f.name+"="+value)
 		}
 	}
-	// -cover is shorthand for -covermode=set.
-	if testCover && testCoverMode == "" {
-		passToTest = setCoverMode("set", passToTest)
+	if testCover {
+		if testCoverMode == "" {
+			testCoverMode = "set"
+		}
+		passToTest = append(passToTest, "-test.covermode", testCoverMode)
 	}
 	// Tell the test what directory we're running in, so it can write the profiles there.
 	if testProfile && outputDir == "" {
@@ -208,24 +216,6 @@ func testFlags(args []string) (packageNames, passToTest []string) {
 	return
 }
 
-// setCoverMode sets the cover mode if not already specified; it captures the default behavior and
-// canonicalizes the coverage flags to pass to the test binary.
-func setCoverMode(mode string, passToTest []string) []string {
-	if testCoverMode != "" {
-		return passToTest
-	}
-	switch mode {
-	case "set", "count", "atomic":
-		testCoverMode = mode
-	default:
-		fatalf("invalid flag argument for -cover: %q", mode)
-	}
-	testCover = true
-	// Guarantee we see the coverage statistics. Doesn't turn -v on generally; tricky. TODO?
-	testV = true
-	return append(passToTest, "-test.covermode", "set")
-}
-
 // testFlag sees if argument i is a known flag and returns its definition, value, and whether it consumed an extra word.
 func testFlag(args []string, i int) (f *testFlagSpec, value string, extra bool) {
 	arg := args[i]