Error on tests ineligible for promotion to conformance

If there are tags in the test name that describe qualities of the
test that make it ineligible for conformance, raise an error. This
is basically the "skip list" that heptio's e2e image used to use.

Thankfully all of our existing Conformance tests lack these tags. I
considered added [Slow] to the list, but let's save that for another
day.

test/conformance/walk_test.go

@@ -17,6 +17,7 @@ limitations under the License.
 package main
 
 import (
+	"fmt"
 	"reflect"
 	"testing"
 )
@@ -127,3 +128,57 @@ func TestNormalizeTestNames(t *testing.T) {
 		}
 	}
 }
+
+func TestValidateTestName(t *testing.T) {
+	testCases := []struct {
+		testName  string
+		tagString string
+	}{
+		{
+			"a test case with no tags",
+			"",
+		},
+		{
+			"a test case with valid tags [LinuxOnly] [NodeConformance] [Serial]",
+			"",
+		},
+		{
+			"a flaky test case that is invalid [Flaky]",
+			"[Flaky]",
+		},
+		{
+			"a disruptive test case that is invalid [Disruptive]",
+			"[Disruptive]",
+		},
+		{
+			"a feature test case that is invalid [Feature:Awesome]",
+			"[Feature:Awesome]",
+		},
+		{
+			"an alpha test case that is invalid [Alpha]",
+			"[Alpha]",
+		},
+		{
+			"a test case with multiple invalid tags [Flaky][Disruptive] [Feature:Awesome] [Alpha]",
+			"[Flaky],[Disruptive],[Feature:Awesome],[Alpha]",
+		},
+		{
+			"[sig-awesome] [Disruptive] a test case with valid and invalid tags [Alpha] [Serial] [Flaky]",
+			"[Disruptive],[Alpha],[Flaky]",
+		},
+	}
+	for i, tc := range testCases {
+		err := validateTestName(tc.testName)
+		if err != nil {
+			if tc.tagString == "" {
+				t.Errorf("test case[%d]: expected no validate error, got %q", i, err.Error())
+			} else {
+				expectedMsg := fmt.Sprintf("'%s' cannot have invalid tags %s", tc.testName, tc.tagString)
+				actualMsg := err.Error()
+				if actualMsg != expectedMsg {
+					t.Errorf("test case[%d]: expected error message %q, got %q", i, expectedMsg, actualMsg)
+				}
+			}
+		}
+	}
+}