Add integration tests for 'more' and 'most' used as pagers

tests/integration_tests.rs

@@ -1,6 +1,7 @@
 use assert_cmd::Command;
 use predicates::{prelude::predicate, str::PredicateStrExt};
-use std::path::Path;
+use std::env;
+use std::path::{Path, PathBuf};
 use std::str::from_utf8;
 
 const EXAMPLES_DIR: &str = "tests/examples";
@@ -23,6 +24,61 @@ fn bat() -> Command {
     cmd
 }
 
+/// For some tests we want mocked versions of some pagers
+/// This fn returns the absolute path to the directory with these mocked pagers
+fn get_mocked_pagers_dir() -> PathBuf {
+    let cargo_manifest_dir = env::var("CARGO_MANIFEST_DIR").expect("Missing CARGO_MANIFEST_DIR");
+    Path::new(&cargo_manifest_dir)
+        .join("tests")
+        .join("mocked-pagers")
+}
+
+/// Prepends a directory to the PATH environment variable
+/// Returns the original value for later restoration
+fn prepend_dir_to_path_env_var(dir: PathBuf) -> String {
+    // Get current PATH
+    let original_path = env::var("PATH").expect("No PATH?!");
+
+    // Add the new dir first
+    let mut split_paths = env::split_paths(&original_path).collect::<Vec<_>>();
+    split_paths.insert(0, dir);
+
+    // Set PATH with the new dir
+    let new_path = env::join_paths(split_paths).expect("Failed to join paths");
+    env::set_var("PATH", new_path);
+
+    // Return the original value for later restoration of it
+    original_path
+}
+
+/// Helper to restore the value of PATH
+fn restore_path(original_path: String) {
+    env::set_var("PATH", original_path);
+}
+
+/// Allows test to run that require our mocked versions of 'more' and 'most'
+/// in PATH. Temporarily changes PATH while the test code runs, and then restore it
+/// to avoid pollution of global state
+fn with_mocked_versions_of_more_and_most_in_path(actual_test: fn()) {
+    let original_path = prepend_dir_to_path_env_var(get_mocked_pagers_dir());
+
+    // Make sure our own variants of 'more' and 'most' is used
+    Command::new("more")
+        .assert()
+        .success()
+        .stdout("I am more\n");
+    Command::new("most")
+        .assert()
+        .success()
+        .stdout("I am most\n");
+
+    // Now run the actual test
+    actual_test();
+
+    // Make sure to restore PATH since it is global state
+    restore_path(original_path);
+}
+
 #[test]
 fn basic() {
     bat()
@@ -415,28 +471,77 @@ fn pager_value_bat() {
         .failure();
 }
 
+/// We shall use less instead of most if PAGER is used since PAGER
+/// is a generic env var
 #[test]
-fn pager_most() {
-    bat()
-        .env("PAGER", "most")
-        .arg("--paging=always")
-        .arg("test.txt")
-        .assert()
-        .success()
-        .stdout(predicate::eq("hello world\n").normalize());
-    // TODO: How to ensure less is used?
+fn pager_most_from_pager_env_var() {
+    with_mocked_versions_of_more_and_most_in_path(|| {
+        // If the output is not "I am most\n" then we know 'most' is not used
+        bat()
+            .env("PAGER", "most")
+            .arg("--paging=always")
+            .arg("test.txt")
+            .assert()
+            .success()
+            .stdout(predicate::eq("hello world\n").normalize());
+    });
 }
 
+/// If the bat-specific BAT_PAGER is used, obey the wish of the user
+/// and allow 'most'
+#[test]
+fn pager_most_from_bat_pager_env_var() {
+    with_mocked_versions_of_more_and_most_in_path(|| {
+        bat()
+            .env("BAT_PAGER", "most")
+            .arg("--paging=always")
+            .arg("test.txt")
+            .assert()
+            .success()
+            .stdout(predicate::eq("I am most\n").normalize());
+    });
+}
+
+/// Same reasoning with --pager as with BAT_PAGER
+#[test]
+fn pager_most_from_pager_arg() {
+    with_mocked_versions_of_more_and_most_in_path(|| {
+        bat()
+            .arg("--paging=always")
+            .arg("--pager=most")
+            .arg("test.txt")
+            .assert()
+            .success()
+            .stdout(predicate::eq("I am most\n").normalize());
+    });
+}
+
+/// Make sure the logic for 'most' applies even if an argument is passed
 #[test]
 fn pager_most_with_arg() {
-    bat()
-        .env("PAGER", "most -w")
-        .arg("--paging=always")
-        .arg("test.txt")
-        .assert()
-        .success()
-        .stdout(predicate::eq("hello world\n").normalize());
-    // TODO: How to ensure less is used?
+    with_mocked_versions_of_more_and_most_in_path(|| {
+        bat()
+            .env("PAGER", "most -w")
+            .arg("--paging=always")
+            .arg("test.txt")
+            .assert()
+            .success()
+            .stdout(predicate::eq("hello world\n").normalize());
+    });
+}
+
+/// Sanity check that 'more' is treated like 'most'
+#[test]
+fn pager_more() {
+    with_mocked_versions_of_more_and_most_in_path(|| {
+        bat()
+            .env("PAGER", "more")
+            .arg("--paging=always")
+            .arg("test.txt")
+            .assert()
+            .success()
+            .stdout(predicate::eq("hello world\n").normalize());
+    });
 }
 
 #[test]

tests/mocked-pagers/more

@@ -0,0 +1,2 @@
+#!/usr/bin/env bash
+echo "I am more"

tests/mocked-pagers/most

@@ -0,0 +1,2 @@
+#!/usr/bin/env bash
+echo "I am most"