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dstudstu
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Add Comparator trait (#872)
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Lines changed: 632 additions & 53 deletions

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‎cargo-insta/tests/functional/comparator.rs‎

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//! Functional tests for custom [`Comparator`] implementations.
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use crate::TestFiles;
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/// Test that a custom comparator can override default matching behavior.
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#[test]
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fn test_custom_comparator_inline() {
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let test_project = TestFiles::new()
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.add_file(
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"Cargo.toml",
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r#"
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[package]
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name = "test_custom_comparator_inline"
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version = "0.1.0"
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edition = "2021"
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[dependencies]
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insta = { path = '$PROJECT_PATH' }
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"#
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.to_string(),
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)
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.add_file(
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"src/lib.rs",
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r#"
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#[cfg(test)]
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mod tests {
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use insta::{Comparator, Snapshot, with_settings, assert_snapshot};
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/// A comparator that ignores whitespace differences.
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struct WhitespaceInsensitiveComparator;
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impl Comparator for WhitespaceInsensitiveComparator {
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fn matches(&self, reference: &Snapshot, test: &Snapshot) -> bool {
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match (reference.as_text(), test.as_text()) {
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(Some(a), Some(b)) => {
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let a_normalized: String = a.to_string().split_whitespace().collect();
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let b_normalized: String = b.to_string().split_whitespace().collect();
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a_normalized == b_normalized
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}
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_ => false,
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}
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}
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fn dyn_clone(&self) -> Box<dyn Comparator> {
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Box::new(WhitespaceInsensitiveComparator)
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}
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}
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#[test]
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fn test_whitespace_insensitive() {
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// The value has single spaces, reference has multiple - custom comparator should match
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let value = "hello world";
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with_settings!({comparator => Box::new(WhitespaceInsensitiveComparator)}, {
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assert_snapshot!(value, @"hello world");
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});
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}
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}
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"#
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.to_string(),
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)
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.create_project();
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let output = test_project
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.insta_cmd()
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.args(["test", "--", "--nocapture"])
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.output()
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.unwrap();
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assert!(
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output.status.success(),
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"Test failed: {}",
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String::from_utf8_lossy(&output.stderr)
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);
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}
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/// Test that a custom comparator works with file snapshots.
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#[test]
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fn test_custom_comparator_file_snapshot() {
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let test_project = TestFiles::new()
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.add_file(
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"Cargo.toml",
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r#"
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[package]
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name = "test_custom_comparator_file"
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version = "0.1.0"
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edition = "2021"
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[dependencies]
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insta = { path = '$PROJECT_PATH' }
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"#
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.to_string(),
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)
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.add_file(
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"src/snapshots/test_custom_comparator_file__tests__file_snapshot.snap",
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r#"---
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source: src/lib.rs
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expression: value
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---
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hello world
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"#
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.to_string(),
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)
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.add_file(
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"src/lib.rs",
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r#"
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#[cfg(test)]
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mod tests {
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use insta::{Comparator, Snapshot, with_settings, assert_snapshot};
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/// A comparator that ignores whitespace differences.
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struct WhitespaceInsensitiveComparator;
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impl Comparator for WhitespaceInsensitiveComparator {
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fn matches(&self, reference: &Snapshot, test: &Snapshot) -> bool {
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match (reference.as_text(), test.as_text()) {
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(Some(a), Some(b)) => {
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let a_normalized: String = a.to_string().split_whitespace().collect();
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let b_normalized: String = b.to_string().split_whitespace().collect();
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a_normalized == b_normalized
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}
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_ => false,
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}
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}
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fn dyn_clone(&self) -> Box<dyn Comparator> {
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Box::new(WhitespaceInsensitiveComparator)
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}
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}
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#[test]
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fn test_file_snapshot() {
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// The value has single spaces, stored snapshot has multiple - should match
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let value = "hello world";
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with_settings!({comparator => Box::new(WhitespaceInsensitiveComparator)}, {
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assert_snapshot!("file_snapshot", value);
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});
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}
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}
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"#
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.to_string(),
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)
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.create_project();
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let output = test_project
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.insta_cmd()
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.args(["test", "--", "--nocapture"])
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.output()
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.unwrap();
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assert!(
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output.status.success(),
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"Test failed: {}",
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String::from_utf8_lossy(&output.stderr)
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);
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}
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/// Test that a custom comparator that rejects a match causes a test failure.
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#[test]
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fn test_custom_comparator_failure() {
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let test_project = TestFiles::new()
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.add_file(
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"Cargo.toml",
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r#"
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[package]
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name = "test_custom_comparator_failure"
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version = "0.1.0"
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edition = "2021"
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[dependencies]
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insta = { path = '$PROJECT_PATH' }
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"#
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.to_string(),
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)
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.add_file(
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"src/lib.rs",
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r#"
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#[cfg(test)]
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mod tests {
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use insta::{Comparator, Snapshot, with_settings, assert_snapshot};
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/// A comparator that always rejects.
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struct AlwaysFailComparator;
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impl Comparator for AlwaysFailComparator {
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fn matches(&self, _reference: &Snapshot, _test: &Snapshot) -> bool {
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false
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}
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fn dyn_clone(&self) -> Box<dyn Comparator> {
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Box::new(AlwaysFailComparator)
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}
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}
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#[test]
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fn test_comparator_rejects() {
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with_settings!({comparator => Box::new(AlwaysFailComparator)}, {
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assert_snapshot!("value", @"value");
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});
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}
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}
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"#
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.to_string(),
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)
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.create_project();
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let output = test_project
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.insta_cmd()
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.args(["test", "--", "--nocapture"])
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.output()
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.unwrap();
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assert!(
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!output.status.success(),
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"Test should have failed but passed"
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);
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}
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/// Test that matches_fully is called when INSTA_REQUIRE_FULL_MATCH is set.
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#[test]
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fn test_matches_fully_with_env_var() {
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let test_project = TestFiles::new()
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.add_file(
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"Cargo.toml",
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r#"
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[package]
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name = "test_matches_fully"
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version = "0.1.0"
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edition = "2021"
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[dependencies]
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insta = { path = '$PROJECT_PATH' }
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"#
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.to_string(),
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)
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.add_file(
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"src/lib.rs",
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r#"
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#[cfg(test)]
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mod tests {
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use std::sync::atomic::{AtomicBool, Ordering};
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use insta::{Comparator, Snapshot, with_settings, assert_snapshot};
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static MATCHES_FULLY_CALLED: AtomicBool = AtomicBool::new(false);
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struct TrackingComparator;
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impl Comparator for TrackingComparator {
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fn matches(&self, _reference: &Snapshot, _test: &Snapshot) -> bool {
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true
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}
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fn matches_fully(&self, _reference: &Snapshot, _test: &Snapshot) -> bool {
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MATCHES_FULLY_CALLED.store(true, Ordering::SeqCst);
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true
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}
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fn dyn_clone(&self) -> Box<dyn Comparator> {
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Box::new(TrackingComparator)
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}
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}
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#[test]
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fn test_tracking() {
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with_settings!({comparator => Box::new(TrackingComparator)}, {
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assert_snapshot!("value", @"value");
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});
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// When INSTA_REQUIRE_FULL_MATCH=1 is set, matches_fully should be called
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assert!(MATCHES_FULLY_CALLED.load(Ordering::SeqCst), "matches_fully was not called");
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}
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}
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"#
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.to_string(),
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)
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.create_project();
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let output = test_project
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.insta_cmd()
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.args(["test", "--", "--nocapture"])
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.env("INSTA_REQUIRE_FULL_MATCH", "1")
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.output()
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.unwrap();
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assert!(
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output.status.success(),
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"Test failed: {}",
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String::from_utf8_lossy(&output.stderr)
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);
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}
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/// Test that comparator setting is inherited in nested with_settings! blocks.
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#[test]
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fn test_comparator_inheritance() {
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let test_project = TestFiles::new()
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.add_file(
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"Cargo.toml",
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r#"
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[package]
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name = "test_comparator_inheritance"
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version = "0.1.0"
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edition = "2021"
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[dependencies]
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insta = { path = '$PROJECT_PATH' }
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"#
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.to_string(),
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)
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.add_file(
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"src/lib.rs",
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r#"
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#[cfg(test)]
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mod tests {
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use insta::{Comparator, Snapshot, with_settings, assert_snapshot};
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/// Always passes.
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struct AlwaysPassComparator;
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impl Comparator for AlwaysPassComparator {
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fn matches(&self, _reference: &Snapshot, _test: &Snapshot) -> bool {
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true
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}
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fn dyn_clone(&self) -> Box<dyn Comparator> {
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Box::new(AlwaysPassComparator)
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}
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}
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#[test]
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fn test_nested_settings() {
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with_settings!({comparator => Box::new(AlwaysPassComparator)}, {
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// Outer block has custom comparator
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assert_snapshot!("outer", @"anything");
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with_settings!({description => "inner block"}, {
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// Inner block should inherit the comparator
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assert_snapshot!("inner", @"different content");
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});
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});
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}
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}
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"#
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.to_string(),
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)
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.create_project();
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let output = test_project
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.insta_cmd()
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.args(["test", "--", "--nocapture"])
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.output()
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.unwrap();
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assert!(
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output.status.success(),
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"Test failed: {}",
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String::from_utf8_lossy(&output.stderr)
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);
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}

‎cargo-insta/tests/functional/main.rs‎

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Original file line numberDiff line numberDiff line change
@@ -70,6 +70,7 @@ use tempfile::TempDir;
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mod back_compat;
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mod binary;
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mod comparator;
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mod delete_pending;
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mod glob_filter;
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mod inline;

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