Run coverage when test-coverage.sh is modified

ci/affects-files.sh

@@ -0,0 +1,30 @@
+#!/usr/bin/env bash
+#
+# Checks if a CI build affects one or more path patterns.  Each command-line
+# argument is checked in series.
+#
+# Bash regular expresses are permitted in the pattern, and the colon (':')
+# character is guaranteed to appear before and after each affected file (and thus
+# can be used as an anchor), eg:
+#     .rs:    -- any file or directory ending in .rs
+#     .rs     -- also matches foo.rs.bar
+#     :snap/  -- anything under the snap/ subdirectory
+#     snap/   -- also matches foo/snap/
+#
+
+if ci/is-pr.sh; then
+  affectedFiles="$(buildkite-agent meta-data get affected_files)"
+  echo "Affected files in this PR: $affectedFiles"
+
+  for pattern in "$@"; do
+    if [[ ":$affectedFiles:" =~ $pattern ]]; then
+      exit 0
+    fi
+  done
+
+  exit 1
+fi
+
+# affected_files metadata is not currently available for non-PR builds, so assume
+# the worse (affected)
+exit 0