diff --git a/src/tests/mod.rs b/src/tests/mod.rs
index 8c9a5392..aa2f41af 100644
--- a/src/tests/mod.rs
+++ b/src/tests/mod.rs
@@ -1,6 +1,6 @@
 extern crate test_generator;
-use heraclitus_compiler::prelude::Message;
 use crate::compiler::{AmberCompiler, CompilerOptions};
+use heraclitus_compiler::prelude::Message;
 use itertools::Itertools;
 use pretty_assertions::assert_eq;
 use std::fs;
@@ -14,12 +14,14 @@ mod stdlib;
 mod validity;
 mod erroring;
 
+const SUCCEEDED: &str = "Succeeded";
+
 pub enum TestOutcomeTarget {
     Success,
     Failure,
 }
 
-pub fn eval_amber_code(code: &str) -> Result<String, Message> {
+fn eval_amber(code: &str) -> Result<String, Message> {
     let options = CompilerOptions::default();
     let mut compiler = AmberCompiler::new(code.to_string(), None, options);
     compiler.test_eval()
@@ -27,26 +29,28 @@ pub fn eval_amber_code(code: &str) -> Result<String, Message> {
 
 /// Tests script output in case of success or failure
 pub fn test_amber(code: &str, result: &str, target: TestOutcomeTarget) {
-    let evaluated = eval_amber_code(code);
+    let evaluated = eval_amber(code);
     match target {
         TestOutcomeTarget::Success => match evaluated {
             Ok(stdout) => {
-                assert_eq!(
-                    stdout.trim_end_matches('\n'),
-                    result.trim_end_matches('\n'),
-                )
-            },
+                let stdout = stdout.trim_end_matches('\n');
+                if stdout != SUCCEEDED {
+                    let result = result.trim_end_matches('\n');
+                    assert_eq!(stdout, result)
+                }
+            }
             Err(err) => {
                 panic!("ERROR: {}", err.message.unwrap())
-            },
+            }
         }
         TestOutcomeTarget::Failure => match evaluated {
             Ok(stdout) => {
                 panic!("Expected error, got: {}", stdout)
-            },
+            }
             Err(err) => {
-                assert_eq!(err.message.expect("Error message expected"), result)
-            },
+                let message = err.message.expect("Error message expected");
+                assert_eq!(message, result)
+            }
         }
     }
 }
@@ -73,7 +77,7 @@ pub fn eval_bash<T: Into<String>>(code: T) -> (String, String) {
     )
 }
 
-/// Extracts the output from the comment of amber code
+/// Extracts the output from the comment of Amber code
 fn extract_output(code: impl Into<String>) -> String {
     code.into()
         .lines()
@@ -86,19 +90,18 @@ fn extract_output(code: impl Into<String>) -> String {
 
 /// Inner test logic for testing script output in case of success or failure
 pub fn script_test(input: &str, target: TestOutcomeTarget) {
-    let code =
-        fs::read_to_string(input).unwrap_or_else(|_| panic!("Failed to open {input} test file"));
-
-    // extract Output from script comment
+    let code = fs::read_to_string(input)
+        .unwrap_or_else(|_| panic!("Failed to open {input} test file"));
+    // Extract output from script comment
     let mut output = extract_output(&code);
-
-    // if output is not in comment, try to read from .output.txt file
+    // If output is not in comment, try to read from .output.txt file
     if output.is_empty() {
-        let output_path = PathBuf::from(input.replace(".ab", ".output.txt"));
-        output = match output_path.exists() {
-            true => fs::read_to_string(output_path)
-                .unwrap_or_else(|_| panic!("Failed to open {input}.output.txt file")),
-            _ => "Succeeded".to_string(),
+        let path = PathBuf::from(input.replace(".ab", ".output.txt"));
+        output = if path.exists() {
+            fs::read_to_string(&path)
+                .unwrap_or_else(|_| panic!("Failed to open {} test file", path.display()))
+        } else {
+            SUCCEEDED.to_string()
         };
     }
     test_amber(&code, &output, target);
diff --git a/src/tests/validity/array_get_negative_index_by_copy.ab b/src/tests/validity/array_get_negative_index_by_copy.ab
new file mode 100644
index 00000000..afa06d00
--- /dev/null
+++ b/src/tests/validity/array_get_negative_index_by_copy.ab
@@ -0,0 +1,30 @@
+// Output
+// Value at -5: ""
+// Value at -4: "zero"
+// Value at -3: "one"
+// Value at -2: "two"
+// Value at -1: "three"
+
+// Replace this with builtin if/when we get around to writing one.
+#[allow_absurd_cast]
+fun bash_version(): Num {
+    let major = trust $ echo "\$\{BASH_VERSINFO[0]}" $ as Num
+    let minor = trust $ echo "\$\{BASH_VERSINFO[1]}" $ as Num
+    return (major * 100) + minor
+}
+
+fun test_index(array) {
+    for index in -5..=-1 {
+        echo "Value at {index}: \"{array[index]}\""
+    }
+}
+
+main {
+    if bash_version() >= 402 {
+        let array = ["zero", "one", "two", "three"]
+        test_index(array)
+    } else {
+        // Negative indexing is not supported before Bash 4.2.
+        echo "Succeeded"
+    }
+}
diff --git a/src/tests/validity/array_get_negative_index_by_ref.ab b/src/tests/validity/array_get_negative_index_by_ref.ab
new file mode 100644
index 00000000..443486a1
--- /dev/null
+++ b/src/tests/validity/array_get_negative_index_by_ref.ab
@@ -0,0 +1,30 @@
+// Output
+// Value at -5: ""
+// Value at -4: "zero"
+// Value at -3: "one"
+// Value at -2: "two"
+// Value at -1: "three"
+
+// Replace this with builtin if/when we get around to writing one.
+#[allow_absurd_cast]
+fun bash_version(): Num {
+    let major = trust $ echo "\$\{BASH_VERSINFO[0]}" $ as Num
+    let minor = trust $ echo "\$\{BASH_VERSINFO[1]}" $ as Num
+    return (major * 100) + minor
+}
+
+fun test_index(ref byref) {
+    for index in -5..=-1 {
+        echo "Value at {index}: \"{byref[index]}\""
+    }
+}
+
+main {
+    if bash_version() >= 402 {
+        let array = ["zero", "one", "two", "three"]
+        test_index(array)
+    } else {
+        // Negative indexing is not supported before Bash 4.2.
+        echo "Succeeded"
+    }
+}
diff --git a/src/tests/validity/array_get_negative_index_local.ab b/src/tests/validity/array_get_negative_index_local.ab
new file mode 100644
index 00000000..3ed56631
--- /dev/null
+++ b/src/tests/validity/array_get_negative_index_local.ab
@@ -0,0 +1,29 @@
+// Output
+// Value at -5: ""
+// Value at -4: "zero"
+// Value at -3: "one"
+// Value at -2: "two"
+// Value at -1: "three"
+
+// Replace this with builtin if/when we get around to writing one.
+#[allow_absurd_cast]
+fun bash_version(): Num {
+    let major = trust $ echo "\$\{BASH_VERSINFO[0]}" $ as Num
+    let minor = trust $ echo "\$\{BASH_VERSINFO[1]}" $ as Num
+    return (major * 100) + minor
+}
+
+main {
+    if bash_version() >= 402 {
+        // Do not use loop; we want to test compile time arithmetic.
+        let array = ["zero", "one", "two", "three"]
+        echo "Value at -5: \"{array[-5]}\""
+        echo "Value at -4: \"{array[-4]}\""
+        echo "Value at -3: \"{array[-3]}\""
+        echo "Value at -2: \"{array[-2]}\""
+        echo "Value at -1: \"{array[-1]}\""
+    } else {
+        // Negative indexing is not supported before Bash 4.2.
+        echo "Succeeded"
+    }
+}
diff --git a/src/tests/validity/array_get_index_by_copy.ab b/src/tests/validity/array_get_positive_index_by_copy.ab
similarity index 67%
rename from src/tests/validity/array_get_index_by_copy.ab
rename to src/tests/validity/array_get_positive_index_by_copy.ab
index e1394566..0a246b42 100644
--- a/src/tests/validity/array_get_index_by_copy.ab
+++ b/src/tests/validity/array_get_positive_index_by_copy.ab
@@ -1,9 +1,4 @@
 // Output
-// Value at -5: ""
-// Value at -4: "zero"
-// Value at -3: "one"
-// Value at -2: "two"
-// Value at -1: "three"
 // Value at 0: "zero"
 // Value at 1: "one"
 // Value at 2: "two"
@@ -11,7 +6,7 @@
 // Value at 4: ""
 
 fun test_index(array) {
-    for index in -5..=4 {
+    for index in 0..=4 {
         echo "Value at {index}: \"{array[index]}\""
     }
 }
diff --git a/src/tests/validity/array_get_index_by_ref.ab b/src/tests/validity/array_get_positive_index_by_ref.ab
similarity index 67%
rename from src/tests/validity/array_get_index_by_ref.ab
rename to src/tests/validity/array_get_positive_index_by_ref.ab
index 6c2e7b4d..889af2ed 100644
--- a/src/tests/validity/array_get_index_by_ref.ab
+++ b/src/tests/validity/array_get_positive_index_by_ref.ab
@@ -1,9 +1,4 @@
 // Output
-// Value at -5: ""
-// Value at -4: "zero"
-// Value at -3: "one"
-// Value at -2: "two"
-// Value at -1: "three"
 // Value at 0: "zero"
 // Value at 1: "one"
 // Value at 2: "two"
@@ -11,7 +6,7 @@
 // Value at 4: ""
 
 fun test_index(ref byref) {
-    for index in -5..=4 {
+    for index in 0..=4 {
         echo "Value at {index}: \"{byref[index]}\""
     }
 }
diff --git a/src/tests/validity/array_get_index_local.ab b/src/tests/validity/array_get_positive_index_local.ab
similarity index 57%
rename from src/tests/validity/array_get_index_local.ab
rename to src/tests/validity/array_get_positive_index_local.ab
index 9ad9dd92..ed094170 100644
--- a/src/tests/validity/array_get_index_local.ab
+++ b/src/tests/validity/array_get_positive_index_local.ab
@@ -1,9 +1,4 @@
 // Output
-// Value at -5: ""
-// Value at -4: "zero"
-// Value at -3: "one"
-// Value at -2: "two"
-// Value at -1: "three"
 // Value at 0: "zero"
 // Value at 1: "one"
 // Value at 2: "two"
@@ -13,11 +8,6 @@
 main {
     // Do not use loop; we want to test compile time arithmetic.
     let array = ["zero", "one", "two", "three"]
-    echo "Value at -5: \"{array[-5]}\""
-    echo "Value at -4: \"{array[-4]}\""
-    echo "Value at -3: \"{array[-3]}\""
-    echo "Value at -2: \"{array[-2]}\""
-    echo "Value at -1: \"{array[-1]}\""
     echo "Value at 0: \"{array[0]}\""
     echo "Value at 1: \"{array[1]}\""
     echo "Value at 2: \"{array[2]}\""