Add first integration test

The simple test solution is on the ebuild generated for cargo-ebuild
itself. After editing cargo.toml or `cargo update` is necessary to
upadate the test in `test/integration.rs`.

.gitignore

@@ -1,2 +1,3 @@
 target
 *.rs.bk
+*.ebuild

Cargo.toml

@@ -25,3 +25,7 @@ log = "0.4.0"
 env_logger = "0.5.10"
 cargo_metadata = "0.5.4"
 toml = "0.4.6"
+
+[dev-dependencies]
+assert_cli = "0.6.1"
+tempdir = "0.3.7"

tests/integration.rs

@@ -0,0 +1,131 @@
+extern crate assert_cli;
+extern crate tempdir;
+
+use std::fs::File;
+use std::io::prelude::*;
+use tempdir::TempDir;
+
+#[test]
+fn build() {
+    let ebuild_name = format!("cargo-ebuild-{}.ebuild", env!("CARGO_PKG_VERSION"));
+
+    let build_dir = TempDir::new("build").unwrap();
+    let build_path = build_dir.path().join(&ebuild_name);
+
+    assert_cli::Assert::main_binary()
+        .with_args(&["build", "-o", build_dir.path().to_str().unwrap()])
+        .stdout()
+        .is((format!("Wrote: {}", build_path.display())).as_str())
+        .unwrap();
+
+    let mut build_file = match File::open(build_path) {
+        Err(why) => panic!("couldn't open generated ebuild: {}", why),
+        Ok(f) => f,
+    };
+
+    let mut new_ebuild = String::new();
+    build_file.read_to_string(&mut new_ebuild).unwrap();
+
+    assert_eq!(new_ebuild, TEST_EBUILD);
+}
+
+
+const TEST_EBUILD: &str = r#"# Copyright 2017-2018 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+
+# Auto-Generated by cargo-ebuild 0.1.6-pre
+
+EAPI=6
+
+CRATES="
+aho-corasick-0.6.4
+ansi_term-0.11.0
+assert_cli-0.6.1
+atty-0.2.10
+backtrace-0.3.8
+backtrace-sys-0.1.23
+bitflags-1.0.3
+cargo-ebuild-0.1.6-pre
+cargo_metadata-0.5.6
+cc-1.0.17
+cfg-if-0.1.3
+clap-2.31.2
+colored-1.6.0
+difference-2.0.0
+dtoa-0.4.2
+env_logger-0.5.10
+environment-0.1.1
+error-chain-0.11.0
+failure-0.1.1
+failure_derive-0.1.1
+fuchsia-zircon-0.3.3
+fuchsia-zircon-sys-0.3.3
+human-panic-1.0.0
+humantime-1.1.1
+itoa-0.4.1
+lazy_static-0.2.11
+lazy_static-1.0.1
+libc-0.2.42
+log-0.4.2
+memchr-2.0.1
+os_type-2.0.0
+proc-macro2-0.4.6
+quick-error-1.2.2
+quote-0.3.15
+quote-0.6.3
+rand-0.4.2
+redox_syscall-0.1.40
+redox_termios-0.1.1
+regex-0.2.11
+regex-1.0.0
+regex-syntax-0.5.6
+regex-syntax-0.6.0
+remove_dir_all-0.5.1
+rustc-demangle-0.1.8
+semver-0.9.0
+semver-parser-0.7.0
+serde-1.0.66
+serde_derive-1.0.66
+serde_json-1.0.20
+strsim-0.7.0
+structopt-0.2.10
+structopt-derive-0.2.10
+syn-0.11.11
+syn-0.14.2
+synom-0.11.3
+synstructure-0.6.1
+tempdir-0.3.7
+termcolor-0.3.6
+termion-1.5.1
+textwrap-0.9.0
+thread_local-0.3.5
+time-0.1.40
+toml-0.4.6
+ucd-util-0.1.1
+unicode-width-0.1.5
+unicode-xid-0.0.4
+unicode-xid-0.1.0
+unreachable-1.0.0
+utf8-ranges-1.0.0
+uuid-0.6.5
+vec_map-0.8.1
+void-1.0.2
+winapi-0.3.5
+winapi-i686-pc-windows-gnu-0.4.0
+winapi-x86_64-pc-windows-gnu-0.4.0
+wincolor-0.1.6"
+
+inherit cargo
+
+DESCRIPTION="Generates an ebuild for a package using the in-tree eclasses."
+HOMEPAGE="https://github.com/cardoe/cargo-ebuild"
+SRC_URI="$(cargo_crate_uris ${CRATES})"
+RESTRICT="mirror"
+LICENSE="MIT/Apache-2.0" # Update to proper Gentoo format
+SLOT="0"
+KEYWORDS="~amd64"
+IUSE=""
+
+DEPEND=""
+RDEPEND=""
+"#;