Feat: Add integration test for file not exist.

Slight find_matches rewrite to use Write trait.

Cargo.lock

@@ -2,6 +2,15 @@
 # It is not intended for manual editing.
 version = 4
 
+[[package]]
+name = "aho-corasick"
+version = "1.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e60d3430d3a69478ad0993f19238d2df97c507009a52b3c10addcd7f6bcb916"
+dependencies = [
+ "memchr",
+]
+
 [[package]]
 name = "anstream"
 version = "0.6.19"
@@ -52,6 +61,45 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "anyhow"
+version = "1.0.98"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e16d2d3311acee920a9eb8d33b8cbc1787ce4a264e85f964c2404b969bdcd487"
+
+[[package]]
+name = "assert_cmd"
+version = "2.0.17"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2bd389a4b2970a01282ee455294913c0a43724daedcd1a24c3eb0ec1c1320b66"
+dependencies = [
+ "anstyle",
+ "bstr",
+ "doc-comment",
+ "libc",
+ "predicates",
+ "predicates-core",
+ "predicates-tree",
+ "wait-timeout",
+]
+
+[[package]]
+name = "autocfg"
+version = "1.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ace50bade8e6234aa140d9a2f552bbee1db4d353f69b8217bc503490fc1a9f26"
+
+[[package]]
+name = "bstr"
+version = "1.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "234113d19d0d7d613b40e86fb654acf958910802bcceab913a4f9e7cda03b1a4"
+dependencies = [
+ "memchr",
+ "regex-automata",
+ "serde",
+]
+
 [[package]]
 name = "clap"
 version = "4.5.39"
@@ -98,11 +146,60 @@ version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b05b61dc5112cbb17e4b6cd61790d9845d13888356391624cbe7e41efeac1e75"
 
+[[package]]
+name = "difflib"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6184e33543162437515c2e2b48714794e37845ec9851711914eec9d308f6ebe8"
+
+[[package]]
+name = "doc-comment"
+version = "0.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fea41bba32d969b513997752735605054bc0dfa92b4c56bf1189f2e174be7a10"
+
+[[package]]
+name = "env_filter"
+version = "0.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "186e05a59d4c50738528153b83b0b0194d3a29507dfec16eccd4b342903397d0"
+dependencies = [
+ "log",
+ "regex",
+]
+
+[[package]]
+name = "env_logger"
+version = "0.11.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "13c863f0904021b108aa8b2f55046443e6b1ebde8fd4a15c399893aae4fa069f"
+dependencies = [
+ "anstream",
+ "anstyle",
+ "env_filter",
+ "jiff",
+ "log",
+]
+
+[[package]]
+name = "float-cmp"
+version = "0.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b09cf3155332e944990140d967ff5eceb70df778b34f77d8075db46e4704e6d8"
+dependencies = [
+ "num-traits",
+]
+
 [[package]]
 name = "grrs"
 version = "0.1.0"
 dependencies = [
+ "anyhow",
+ "assert_cmd",
  "clap",
+ "env_logger",
+ "log",
+ "predicates",
 ]
 
 [[package]]
@@ -117,12 +214,114 @@ version = "1.70.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7943c866cc5cd64cbc25b2e01621d07fa8eb2a1a23160ee81ce38704e97b8ecf"
 
+[[package]]
+name = "jiff"
+version = "0.2.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a194df1107f33c79f4f93d02c80798520551949d59dfad22b6157048a88cca93"
+dependencies = [
+ "jiff-static",
+ "log",
+ "portable-atomic",
+ "portable-atomic-util",
+ "serde",
+]
+
+[[package]]
+name = "jiff-static"
+version = "0.2.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6c6e1db7ed32c6c71b759497fae34bf7933636f75a251b9e736555da426f6442"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
+[[package]]
+name = "libc"
+version = "0.2.172"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d750af042f7ef4f724306de029d18836c26c1765a54a6a3f094cbd23a7267ffa"
+
+[[package]]
+name = "log"
+version = "0.4.27"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "13dc2df351e3202783a1fe0d44375f7295ffb4049267b0f3018346dc122a1d94"
+
+[[package]]
+name = "memchr"
+version = "2.7.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
+
+[[package]]
+name = "normalize-line-endings"
+version = "0.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "61807f77802ff30975e01f4f071c8ba10c022052f98b3294119f3e615d13e5be"
+
+[[package]]
+name = "num-traits"
+version = "0.2.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "071dfc062690e90b734c0b2273ce72ad0ffa95f0c74596bc250dcfd960262841"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "once_cell_polyfill"
 version = "1.70.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a4895175b425cb1f87721b59f0f286c2092bd4af812243672510e1ac53e2e0ad"
 
+[[package]]
+name = "portable-atomic"
+version = "1.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f84267b20a16ea918e43c6a88433c2d54fa145c92a811b5b047ccbe153674483"
+
+[[package]]
+name = "portable-atomic-util"
+version = "0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d8a2f0d8d040d7848a709caf78912debcc3f33ee4b3cac47d73d1e1069e83507"
+dependencies = [
+ "portable-atomic",
+]
+
+[[package]]
+name = "predicates"
+version = "3.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a5d19ee57562043d37e82899fade9a22ebab7be9cef5026b07fda9cdd4293573"
+dependencies = [
+ "anstyle",
+ "difflib",
+ "float-cmp",
+ "normalize-line-endings",
+ "predicates-core",
+ "regex",
+]
+
+[[package]]
+name = "predicates-core"
+version = "1.0.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "727e462b119fe9c93fd0eb1429a5f7647394014cf3c04ab2c0350eeb09095ffa"
+
+[[package]]
+name = "predicates-tree"
+version = "1.0.12"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "72dd2d6d381dfb73a193c7fca536518d7caee39fc8503f74e7dc0be0531b425c"
+dependencies = [
+ "predicates-core",
+ "termtree",
+]
+
 [[package]]
 name = "proc-macro2"
 version = "1.0.95"
@@ -141,6 +340,55 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "regex"
+version = "1.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b544ef1b4eac5dc2db33ea63606ae9ffcfac26c1416a2806ae0bf5f56b201191"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-automata",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-automata"
+version = "0.4.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "809e8dc61f6de73b46c85f4c96486310fe304c434cfa43669d7b40f711150908"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.8.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2b15c43186be67a4fd63bee50d0303afffcef381492ebe2c5d87f324e1b8815c"
+
+[[package]]
+name = "serde"
+version = "1.0.219"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5f0e2c6ed6606019b4e29e69dbaba95b11854410e5347d525002456dbbb786b6"
+dependencies = [
+ "serde_derive",
+]
+
+[[package]]
+name = "serde_derive"
+version = "1.0.219"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5b0276cf7f2c73365f7157c8123c21cd9a50fbbd844757af28ca1f5925fc2a00"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "strsim"
 version = "0.11.1"
@@ -158,6 +406,12 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "termtree"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f50febec83f5ee1df3015341d8bd429f2d1cc62bcba7ea2076759d315084683"
+
 [[package]]
 name = "unicode-ident"
 version = "1.0.18"
@@ -170,6 +424,15 @@ version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "06abde3611657adf66d383f00b093d7faecc7fa57071cce2578660c9f1010821"
 
+[[package]]
+name = "wait-timeout"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09ac3b126d3914f9849036f826e054cbabdc8519970b8998ddaf3b5bd3c65f11"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "windows-sys"
 version = "0.59.0"

Cargo.toml

@@ -4,4 +4,11 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+anyhow = "1.0.98"
 clap = { version = "4.5.39", features = ["derive"] }
+env_logger = "0.11.8"
+log = "0.4.27"
+
+[dev-dependencies]
+assert_cmd = "2.0.17"
+predicates = "3.1.3"

src/lib.rs

@@ -0,0 +1,18 @@
+use anyhow::Result;
+
+pub fn find_matches(content: &str, pattern: &str, mut writer: impl std::io::Write) -> Result<()> {
+    for line in content.lines() {
+        if line.contains(pattern) {
+            writeln!(writer, "{}", line)?;
+        }
+    }
+    Ok(())
+}
+
+#[test]
+fn find_a_match() -> Result<(), Box<dyn std::error::Error>> {
+    let mut result = Vec::new();
+    find_matches("lorem ipsum\ndolar sit amet", "lorem", &mut result)?;
+    assert_eq!(result, b"lorem ipsum\n");
+    Ok(())
+}

src/main.rs

@@ -1,4 +1,6 @@
+use anyhow::{Context, Result};
 use clap::Parser;
+use log::info;
 
 // Search for a pattern in a file and display the lines that contain it.
 #[derive(Parser)]
@@ -7,14 +9,29 @@ struct Cli {
     path: std::path::PathBuf,
 }
 
-fn main() {
+fn main() -> Result<()> {
+    env_logger::init();
+    info!("starting up");
     let args = Cli::parse();
 
-    let content = std::fs::read_to_string(&args.path).expect("Could not read file.");
+    let content = std::fs::read_to_string(&args.path)
+        .with_context(|| format!("could not read file `{}`.", args.path.display()))?;
 
-    for line in content.lines() {
-        if line.contains(&args.pattern) {
-            println!("{}", line)
-        }
-    }
+    grrs::find_matches(
+        content.as_str(),
+        args.pattern.as_str(),
+        &mut std::io::stdout(),
+    )?;
+
+    Ok(())
+}
+
+#[allow(dead_code)]
+fn answer() -> i32 {
+    return 42;
+}
+
+#[test]
+fn check_answer_validity() {
+    assert_eq!(answer(), 42);
 }

tests/cli.rs

@@ -0,0 +1,15 @@
+use assert_cmd::prelude::*; // Add methods on commands
+use predicates::prelude::*; // Used for writing assertions
+use std::process::Command; // Run programs
+
+#[test]
+fn file_doesnt_exist() -> Result<(), Box<dyn std::error::Error>> {
+    let mut cmd = Command::cargo_bin("grrs")?;
+
+    cmd.arg("foobar").arg("test/file/doesnt/exist");
+    cmd.assert()
+        .failure()
+        .stderr(predicate::str::contains("could not read file"));
+
+    Ok(())
+}