Added initial testing documentation

tests/README.txt

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+This document describes the testing done in the OSIPI TF2.4 IVIM repository
+
+
+-- Outline --
+1. Testing philosophy
+2. Testing structure
+3. Testing results
+
+
+
+-- Testing philosophy --
+Testing is integral to the repository.
+There are many different contributions from many different people and only through diligent testing can they all be ensured to work correctly together.
+Automated testing happens on different platforms and versions.
+There are 3 major types of tests we conduct.
+1. Requirements
+    - Runs on each commit
+    - Must pass to merge
+    - All algorithms have the same requirements
+    - E.g. bounds honored, code runs reasonably, properly integrated
+    - Would prevent a merge if not passing
+    - Flexibile input/output
+    - Categories for testing
+        -- Contributions - Some aspects currently tested as unit_test
+            --- Initial bounds are respected
+                ---- Needs implemening
+            --- Initial guess is respected
+                ---- Needs implemening - may no be possible
+            --- Runs reasonably
+                ---- Needs implemening: reduced data size, broadened limits
+            --- Contains information about algorithm
+        -- Wrapper
+            --- Initial guess is in bounds
+            --- Reasonable default bounds - f: [0 1], D >= 0 & D < D*, D* >= 0
+            --- Input size is respected - result is same size as input
+            --- Dictionary is returned - worth explicit testing?
+        -- Phantom - lower priority
+            --- Data can be pulled
+2. Expectations
+    - Run on each merge
+    - Considered warnings
+    - Should not necessarily prevent a merge
+    - Categories for testing
+        -- Determine performance changes from reference run
+            --- Currently implemented but could be made easier to interact with
+            --- Could be made easier and faster
+3. Characterization
+    - Run on demand
+    - Performance of the algorithms
+    - The accuracy and precision of the results
+    - The speed of the generated results
+    - Human readable report of the wrapped algorithms
+    - Categories for testing
+        -- Simulations
+            --- Voxels from tissue and characterize algorithms
+            --- Visualize parameter maps
+        -- True data
+            --- Visualize parameter maps
+            --- Correlations between algorithms - plot the results and differences
+
+-- Testing structure --
+
+* The testing is controlled in several places.
+* The testing itself is done with pytest which parses files for "test_" and runs the appropriate tests.
+* The pytest testing can be done on your own machine by running "python -m pytest".
+** This is configured with pytests.ini and conftest.py
+* Testing on github is controlled by the github actions which are in the workflows folder.
+* Each workflow performs a series of tests, and is defined by the yml file.
+* Each workflow can run at specified times and with specified outputs.
+* Currently the major testing workflows are unit_test.yml and analysis.yml.
+* The unit_test workflow is done frequently and is relativly fast and does some basic algorithm testing.
+* The analysis workflow is done more infrequently with merges to the main branch and does more Expecation testing.
+
+
+-- Testing results --
+The test results are written to several files, most notably an xml file for machine parsing, and a web page for code coverage.
+The "analysis" tests are written to a csv file as well.