diff --git a/coverage/coverage.go b/coverage/coverage.go
new file mode 100644
index 00000000..dc0f3d31
--- /dev/null
+++ b/coverage/coverage.go
@@ -0,0 +1,53 @@
+package coverage
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"reflect"
+	"runtime"
+)
+
+var out io.Writer
+var seen map[string]bool
+
+func init() {
+	var err error
+	out, err = os.OpenFile(os.Getenv("HUB_COVERAGE"), os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0644)
+	if err != nil {
+		panic(err)
+	}
+	seen = make(map[string]bool)
+}
+
+func Record(data interface{}, i int) {
+	_, filename, _, _ := runtime.Caller(1)
+	if !seen[filename] {
+		seen[filename] = true
+		d := reflect.ValueOf(data)
+		count := reflect.ValueOf(d.FieldByName("Count").Interface())
+		total := count.Len()
+		for j := 0; j < total; j++ {
+			write(data, j, 0, filename)
+		}
+	}
+	write(data, i, 1, filename)
+}
+
+func write(data interface{}, i, count int, filename string) {
+	d := reflect.ValueOf(data)
+	pos := reflect.ValueOf(d.FieldByName("Pos").Interface())
+	numStmt := reflect.ValueOf(d.FieldByName("NumStmt").Interface())
+
+	fmt.Fprintf(
+		out,
+		"%s:%d.%d,%d.%d %d %d\n",
+		filename,
+		pos.Index(3*i).Uint(),
+		pos.Index(3*i+2).Uint()&0xFFFF,
+		pos.Index(3*i+1).Uint(),
+		pos.Index(3*i+2).Uint()>>16&0xFFFF,
+		numStmt.Index(i).Uint(),
+		count,
+	)
+}
diff --git a/script/coverage b/script/coverage
new file mode 100755
index 00000000..dc73c758
--- /dev/null
+++ b/script/coverage
@@ -0,0 +1,53 @@
+#!/bin/bash
+set -e
+
+source_files() {
+  script/build files | grep -vE '^\./(coverage|fixtures)/'
+}
+
+prepare() {
+  if ! git diff --quiet; then
+    echo "Error: please commit your changes before continuing." >&2
+    exit 1
+  fi
+
+  local n=0
+  for f in $(source_files); do
+    go tool cover -mode=set -var="LiveCoverage$((++n))" "$f" > "$f"~
+    sed -E '
+      /^package /a\
+      import "github.com/github/hub/coverage"
+      s/(LiveCoverage[0-9]+)\.Count\[([0-9]+)\][^;]+/coverage.Record(\1, \2)/
+    ' < "$f"~ > "$f"
+    rm "$f"~
+  done
+
+  rm -rf "$HUB_COVERAGE"
+  mkdir -p "${HUB_COVERAGE%/*}"
+}
+
+generate() {
+  source_files | xargs git checkout --
+
+  echo 'mode: count' > "$HUB_COVERAGE"~
+  sed -E 's!^.+/(github.com/github/hub/)!\1!' "$HUB_COVERAGE" | awk '
+    { a[substr($0, 0, length()-2)] += $(NF) }
+    END { for (k in a) print k, a[k] }
+  ' >> "$HUB_COVERAGE"~
+
+  go tool cover -func="$HUB_COVERAGE"~ > "${HUB_COVERAGE%.out}.func"
+  if [ -z "$CI" ]; then
+    go tool cover -html="$HUB_COVERAGE"~ -o "${HUB_COVERAGE%.out}.html"
+  fi
+
+  awk '/^total:/ { print $(NF) }' "${HUB_COVERAGE%.out}.func"
+}
+
+case "${1?}" in
+  prepare | generate )
+    "$1"
+    ;;
+  * )
+    exit 1
+    ;;
+esac
diff --git a/script/test b/script/test
index 17acb5de..bcfbbdef 100755
--- a/script/test
+++ b/script/test
@@ -1,30 +1,55 @@
 #!/usr/bin/env bash
-# Usage: script/test
+# Usage: script/test [--coverage [<MIN>]]
 #
 # Run Go and Cucumber test suites for hub.
 
 set -e
 
-case "$1" in
-"" )
-  ;;
--h | --help )
-  sed -ne '/^#/!q;s/.\{1,2\}//;1d;p' < "$0"
-  exit
-  ;;
-* )
-  "$0" --help >&2
-  exit 1
-esac
+while [ $# -gt 0 ]; do
+  case "$1" in
+  --coverage )
+    export HUB_COVERAGE="$PWD/tmp/cover.out"
+    if [ "$2" -gt 0 ] 2>/dev/null; then
+      min_coverage="$2"
+      shift 2
+    else
+      min_coverage=1
+      shift 1
+    fi
+    ;;
+  -h | --help )
+    sed -ne '/^#/!q;s/.\{1,2\}//;1d;p' < "$0"
+    exit
+    ;;
+  * )
+    "$0" --help >&2
+    exit 1
+  esac
+done
 
 STATUS=0
 
 trap "exit 1" INT
 
+[ -z "$HUB_COVERAGE" ] || script/coverage prepare
 script/build
 script/build test || STATUS="$?"
 script/ruby-test || STATUS="$?"
 
+if [ -n "$HUB_COVERAGE" ]; then
+  total_coverage="$(script/coverage generate)"
+  echo "Code coverage: $total_coverage"
+  if [ "${total_coverage%.*}" -lt "$min_coverage" ]; then
+    echo "Error: coverage dropped below the minimum treshold of ${min_coverage}%!"
+    if [ -n "$CI" ]; then
+      html_result="${HUB_COVERAGE%.out}.html"
+      html_result="${html_result#$PWD/}"
+      printf 'Please run `script/test --coverage` locally and open `%s` to analyze the results.\n' "$html_result"
+    fi
+    STATUS=1
+  fi
+fi
+
 if [ -n "$CI" ]; then
   make fmt >/dev/null
   if ! git diff -U1 --exit-code; then