From bb0c91683f23cf7cf18ffa0a3c66ea6a2e61ff2c Mon Sep 17 00:00:00 2001
From: Arseny Balobanov <verytable@yandex.ru>
Date: Thu, 19 Mar 2020 01:29:11 +0300
Subject: [PATCH] Adding forgotten coverage helpers.

---
 tools/testtool/commands/coverage.go      | 98 ++++++++++++++++++++++++
 tools/testtool/commands/coverage_test.go | 17 ++++
 2 files changed, 115 insertions(+)
 create mode 100644 tools/testtool/commands/coverage.go
 create mode 100644 tools/testtool/commands/coverage_test.go

diff --git a/tools/testtool/commands/coverage.go b/tools/testtool/commands/coverage.go
new file mode 100644
index 0000000..1f2f538
--- /dev/null
+++ b/tools/testtool/commands/coverage.go
@@ -0,0 +1,98 @@
+package commands
+
+import (
+	"fmt"
+	"go/parser"
+	"go/token"
+	"strconv"
+	"strings"
+
+	"golang.org/x/tools/cover"
+)
+
+// coverageCommentPrefix is a prefix of coverage comment.
+//
+// Coverage comment has the following form:
+//
+// // min coverage: 80.5%
+const coverageCommentPrefix = "min coverage: "
+
+type CoverageRequirements struct {
+	Enabled bool
+	Percent float64
+}
+
+// getCoverageRequirements searches for comment in test files
+// that specifies test coverage requirements.
+//
+// Stops on first matching comment.
+func getCoverageRequirements(rootPackage string) *CoverageRequirements {
+	files := listTestFiles(rootPackage)
+
+	r := &CoverageRequirements{}
+	for _, f := range files {
+		r, _ := searchCoverageComment(f)
+		if r.Enabled {
+			return r
+		}
+	}
+
+	return r
+}
+
+// searchCoverageComment searches for the first occurrence of the comment of the form
+//
+// // min coverage: 80.5%
+//
+// Stops on the first matching comment.
+func searchCoverageComment(fname string) (*CoverageRequirements, error) {
+	fset := token.NewFileSet()
+
+	f, err := parser.ParseFile(fset, fname, nil, parser.ParseComments)
+	if err != nil {
+		return nil, err
+	}
+
+	for _, c := range f.Comments {
+		t := c.Text()
+		if !strings.HasPrefix(t, coverageCommentPrefix) || !strings.HasSuffix(t, "%\n") {
+			continue
+		}
+		t = strings.TrimPrefix(t, coverageCommentPrefix)
+		t = strings.TrimSuffix(t, "%\n")
+		percent, err := strconv.ParseFloat(t, 64)
+		if err != nil {
+			continue
+		}
+		if percent < 0 || percent > 100.0 {
+			continue
+		}
+		return &CoverageRequirements{Enabled: true, Percent: percent}, nil
+	}
+
+	return &CoverageRequirements{}, nil
+}
+
+// calCoverage calculates coverage percent for given coverage profile.
+func calCoverage(profile string) (float64, error) {
+	profiles, err := cover.ParseProfiles(profile)
+	if err != nil {
+		return 0.0, fmt.Errorf("cannot parse coverage profile file %s: %w", profile, err)
+	}
+
+	var total, covered int
+	for _, p := range profiles {
+		for _, block := range p.Blocks {
+			total += block.NumStmt
+			if block.Count > 0 {
+				covered += block.NumStmt
+			}
+		}
+	}
+
+	if total == 0 {
+		return 0.0, nil
+	}
+
+	return float64(covered) / float64(total) * 100, nil
+}
diff --git a/tools/testtool/commands/coverage_test.go b/tools/testtool/commands/coverage_test.go
new file mode 100644
index 0000000..766eae3
--- /dev/null
+++ b/tools/testtool/commands/coverage_test.go
@@ -0,0 +1,17 @@
+package commands
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func Test_getCoverageRequirements(t *testing.T) {
+	r := getCoverageRequirements("../testdata/coverage/sum")
+	require.True(t, r.Enabled)
+	require.Equal(t, 90.0, r.Percent)
+	t.Logf("r: %+v", r)
+	//require.Equal(t,
+	//	absPaths([]string{"sum/private_test.go", "sum/public_test.go"}),
+	//	getCoverageRequirements("../testdata/coverage"))
+}