Extract and report coverage information.

When `go test` is run on multiple packages and with coverage collection
enabled, it appends coverage information to the final result line for
each package.

With this change, properly handle this additional information and add it
into the JUnit XML report as a property of the test suite.

go-junit-report_test.go

@@ -260,6 +260,73 @@ var testCases = []TestCase{
 			},
 		},
 	},
+	{
+		name:       "09-coverage.txt",
+		reportName: "09-report.xml",
+		report: &Report{
+			Packages: []Package{
+				{
+					Name: "package/name",
+					Time: 160,
+					Tests: []*Test{
+						{
+							Name:   "TestZ",
+							Time:   60,
+							Result: PASS,
+							Output: []string{},
+						},
+						{
+							Name:   "TestA",
+							Time:   100,
+							Result: PASS,
+							Output: []string{},
+						},
+					},
+					CoveragePct: "13.37",
+				},
+			},
+		},
+	},
+	{
+		name:       "10-multipkg-coverage.txt",
+		reportName: "10-report.xml",
+		report: &Report{
+			Packages: []Package{
+				{
+					Name: "package1/foo",
+					Time: 400,
+					Tests: []*Test{
+						{
+							Name:   "TestA",
+							Time:   100,
+							Result: PASS,
+							Output: []string{},
+						},
+						{
+							Name:   "TestB",
+							Time:   300,
+							Result: PASS,
+							Output: []string{},
+						},
+					},
+					CoveragePct: "10.0",
+				},
+				{
+					Name: "package2/bar",
+					Time: 4200,
+					Tests: []*Test{
+						{
+							Name:   "TestC",
+							Time:   4200,
+							Result: PASS,
+							Output: []string{},
+						},
+					},
+					CoveragePct: "99.8",
+				},
+			},
+		},
+	},
 }
 
 func TestParser(t *testing.T) {
@@ -321,6 +388,9 @@ func TestParser(t *testing.T) {
 					t.Errorf("Test.Output ==\n%s\n, want\n%s", testOutput, expTestOutput)
 				}
 			}
+			if pkg.CoveragePct != expPkg.CoveragePct {
+				t.Errorf("Package.CoveragePct == %s, want %s", pkg.CoveragePct, expPkg.CoveragePct)
+			}
 		}
 	}
 }