Reintroduce coverage checking for Travis builds

Tarpaulin no longer requires nightly again.

.travis.yml

@@ -1,11 +1,23 @@
 sudo: required
 language: rust
 
+# Dependencies of tarpaulin
+addons:
+  apt:
+    packages:
+      - libssl-dev
+
+
 cache: cargo
 
 install:
   - rustup component add rustfmt-preview
   - rustfmt --version
+  - |
+    if [[ $(cargo tarpaulin --version) != *0.8.4 ]]
+    then
+      cargo install --force cargo-tarpaulin
+    fi
 
 before_script:
   - wget https://github.com/Ortham/testing-plugins/archive/1.4.0.tar.gz
@@ -15,6 +27,9 @@ before_script:
 script:
   - cargo fmt --all -- --check
   - cargo test --all --all-features
+  # Running cbindgen through tarpaulin fails due to an unexpected "metadata"
+  # argument when generating the C header file, so skip the ffi-headers feature.
+  - cargo tarpaulin --all --features compressed-fields --ciserver travis-ci --coveralls $TRAVIS_JOB_ID
   # Need to rebuild the FFI wrapper so that its binary is given a filename
   # without a hash.
   - cargo build --manifest-path ffi/Cargo.toml --features ffi-headers

Cargo.toml

@@ -11,6 +11,7 @@ license = "GPL-3.0"
 
 [badges]
 travis-ci = { repository = "Ortham/esplugin" }
+coveralls = { repository = "Ortham/esplugin" }
 
 [dependencies]
 byteorder = "1.2.0"

README.md

@@ -3,6 +3,7 @@ esplugin
 
 [![Build status](https://ci.appveyor.com/api/projects/status/ukb7ns50fskawwsh/branch/master?svg=true)](https://ci.appveyor.com/project/Ortham/esplugin/branch/master)
 [![Travis Build Status](https://travis-ci.org/Ortham/esplugin.svg?branch=master)](https://travis-ci.org/Ortham/esplugin)
+[![Coverage Status](https://coveralls.io/repos/github/Ortham/esplugin/badge.svg?branch=master)](https://coveralls.io/github/Ortham/esplugin?branch=master)
 [![dependency status](https://deps.rs/repo/github/Ortham/esplugin/status.svg)](https://deps.rs/repo/github/Ortham/esplugin)
 [![docs](https://docs.rs/esplugin/badge.svg)](https://docs.rs/crate/esplugin)