diff --git a/src/context.rs b/src/context.rs
index 2ce55258..251e5e33 100644
--- a/src/context.rs
+++ b/src/context.rs
@@ -43,8 +43,13 @@ pub struct Context<'a> {
     pub shell: Shell,
 
     /// A HashMap of environment variable mocks
+    #[cfg(test)]
     pub env: HashMap<&'a str, String>,
 
+    /// A HashMap of command mocks
+    #[cfg(test)]
+    pub cmd: HashMap<&'a str, Option<CommandOutput>>,
+
     /// Timeout for the execution of commands
     cmd_timeout: Duration,
 }
@@ -114,7 +119,10 @@ impl<'a> Context<'a> {
             dir_contents: OnceCell::new(),
             repo: OnceCell::new(),
             shell,
+            #[cfg(test)]
             env: HashMap::new(),
+            #[cfg(test)]
+            cmd: HashMap::new(),
             cmd_timeout,
         }
     }
@@ -129,21 +137,27 @@ impl<'a> Context<'a> {
     }
 
     // Retrives a environment variable from the os or from a table if in testing mode
+    #[cfg(test)]
     pub fn get_env<K: AsRef<str>>(&self, key: K) -> Option<String> {
-        if cfg!(test) {
-            self.env.get(key.as_ref()).map(|val| val.to_string())
-        } else {
-            env::var(key.as_ref()).ok()
-        }
+        self.env.get(key.as_ref()).map(|val| val.to_string())
+    }
+
+    #[cfg(not(test))]
+    #[inline]
+    pub fn get_env<K: AsRef<str>>(&self, key: K) -> Option<String> {
+        env::var(key.as_ref()).ok()
     }
 
     // Retrives a environment variable from the os or from a table if in testing mode (os version)
+    #[cfg(test)]
     pub fn get_env_os<K: AsRef<str>>(&self, key: K) -> Option<OsString> {
-        if cfg!(test) {
-            self.env.get(key.as_ref()).map(OsString::from)
-        } else {
-            env::var_os(key.as_ref())
-        }
+        self.env.get(key.as_ref()).map(OsString::from)
+    }
+
+    #[cfg(not(test))]
+    #[inline]
+    pub fn get_env_os<K: AsRef<str>>(&self, key: K) -> Option<OsString> {
+        env::var_os(key.as_ref())
     }
 
     /// Convert a `~` in a path to the home directory
@@ -246,7 +260,18 @@ impl<'a> Context<'a> {
     }
 
     /// Execute a command and return the output on stdout and stderr if successful
+    #[inline]
     pub fn exec_cmd(&self, cmd: &str, args: &[&str]) -> Option<CommandOutput> {
+        #[cfg(test)]
+        {
+            let command = match args.len() {
+                0 => cmd.to_owned(),
+                _ => format!("{} {}", cmd, args.join(" ")),
+            };
+            if let Some(output) = self.cmd.get(command.as_str()) {
+                return output.clone();
+            }
+        }
         exec_cmd(cmd, args, self.cmd_timeout)
     }
 }
diff --git a/src/modules/java.rs b/src/modules/java.rs
index 9fa1789b..26745d7d 100644
--- a/src/modules/java.rs
+++ b/src/modules/java.rs
@@ -91,7 +91,7 @@ fn parse_java_version(java_version: &str) -> Option<String> {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::test::ModuleRenderer;
+    use crate::{test::ModuleRenderer, utils::CommandOutput};
     use ansi_term::Color;
     use std::fs::File;
     use std::io;
@@ -179,6 +179,32 @@ mod tests {
         dir.close()
     }
 
+    #[test]
+    fn folder_with_java_file_preview() -> io::Result<()> {
+        let dir = tempfile::tempdir()?;
+        File::create(dir.path().join("Main.java"))?.sync_all()?;
+        let actual = ModuleRenderer::new("java").cmd("java -Xinternalversion", Some(CommandOutput {
+            stdout: "OpenJDK 64-Bit Server VM (16+14) for bsd-aarch64 JRE (16+14), built on Jan 17 2021 07:19:47 by \"brew\" with clang Apple LLVM 12.0.0 (clang-1200.0.32.28)\n".to_owned(),
+            stderr: "".to_owned()
+        })).path(dir.path()).collect();
+        let expected = Some(format!("via {}", Color::Red.dimmed().paint("☕ v16 ")));
+        assert_eq!(expected, actual);
+        dir.close()
+    }
+
+    #[test]
+    fn folder_with_java_file_no_java_installed() -> io::Result<()> {
+        let dir = tempfile::tempdir()?;
+        File::create(dir.path().join("Main.java"))?.sync_all()?;
+        let actual = ModuleRenderer::new("java")
+            .cmd("java -Xinternalversion", None)
+            .path(dir.path())
+            .collect();
+        let expected = Some(format!("via {}", Color::Red.dimmed().paint("☕ ")));
+        assert_eq!(expected, actual);
+        dir.close()
+    }
+
     #[test]
     fn folder_with_class_file() -> io::Result<()> {
         let dir = tempfile::tempdir()?;
diff --git a/src/test/mod.rs b/src/test/mod.rs
index acdc56f4..0cfab591 100644
--- a/src/test/mod.rs
+++ b/src/test/mod.rs
@@ -1,6 +1,6 @@
-use crate::config::StarshipConfig;
 use crate::context::{Context, Shell};
 use crate::logger::StarshipLogger;
+use crate::{config::StarshipConfig, utils::CommandOutput};
 use log::{Level, LevelFilter};
 use once_cell::sync::Lazy;
 use std::io;
@@ -83,6 +83,12 @@ impl<'a> ModuleRenderer<'a> {
         self
     }
 
+    /// Adds the command to the commandv_mocks of the underlying context
+    pub fn cmd(mut self, key: &'a str, val: Option<CommandOutput>) -> Self {
+        self.context.cmd.insert(key, val);
+        self
+    }
+
     pub fn shell(mut self, shell: Shell) -> Self {
         self.context.shell = shell;
         self
diff --git a/src/utils.rs b/src/utils.rs
index 7dfe1406..c9d076ae 100644
--- a/src/utils.rs
+++ b/src/utils.rs
@@ -16,7 +16,7 @@ pub fn read_file<P: AsRef<Path>>(file_name: P) -> Result<String> {
     Ok(data)
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct CommandOutput {
     pub stdout: String,
     pub stderr: String,