docs: add Troubleshoting section (#1463)

Author: mackignacio

README.md

@@ -15,9 +15,7 @@ It supports all features of TypeScript including type-checking. [Read more about
 
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-<!--
-[<img src="./docs/assets/img/troubleshooting.png" align="left" height="24"> Before reporting any issue, be sure to check the troubleshooting page](https://kulshekhar.github.io/ts-jest/user/troubleshooting)
--->
+[<img src="./docs/assets/img/troubleshooting.png" align="left" height="24"> Before reporting any issue, be sure to check the troubleshooting page](TROUBLESHOOTING.md)
 
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TROUBLESHOOTING.md

@@ -0,0 +1,41 @@
+# Troubleshooting
+
+## Running ts-jest on CI tools
+
+### PROBLEM
+
+Cannot find module "" from ""
+
+### SOLUTION
+
+- Check if `rootDir` is referenced correctly. If not add this on your existing jest configuration.
+
+```javascipt
+module.exports = {
+  ...
+   roots: ["<rootDir>"]
+}
+```
+
+- Check if module directories are included on your jest configuration. If not add this on your existing jest configuration.
+
+```javascipt
+module.exports = {
+  ...
+  moduleDirectories: ["node_modules","<module-directory>"],
+  modulePaths: ["<path-of-module>"],
+}
+```
+
+- Check if module name is properly mapped and can be referenced by jest. If not, you can define moduleNameMapper for your jest configuration.
+
+```javascipt
+module.exports = {
+  ...
+  moduleNameMapper: {
+    "<import-path>": "<rootDir>/<real-physical-path>",
+  },
+}
+```
+
+- Check github folder names if its identical to you local folder names. Sometimes github never updates your folder names even if you rename it locally. If this happens rename your folders via github or use this command `git mv <source> <destination>` and commit changes.