new Assignment_C README.md, images

.gitignore

@@ -131,5 +131,7 @@ dmypy.json
 
 # project-specific files
 README_init.md
-**/*_sol.py
 
+# solution files and .py files in project directory
+**/*_sol.py
+/*.py

C_expressions/README.md

+# Assignment C: Python Expressions &nbsp; (<span style="color:red">16 Pts</span>)
+
+This assignment demonstrates Python's powerful (*"one-liner"*) expressions.
+
+### Challenges
+1. [Challenge 1:](#1-challenge-1-create-new-project) Create New Project
+1. [Challenge 2:](#2-challenge-2-run-code) Run Code
+1. [Challenge 3:](#3-challenge-3-run-unit-tests) Run Unit Tests
+1. [Challenge 4:](#4-challenge-4-write-expressions) Write Expressions
+1. [Challenge 5:](#5-challenge-5-final-test) Final Test
+
+
+&nbsp;
+### 1.) Challenge 1: Create New Project
+Create a Python project, e.g. named `C_expressions`, and
+[pull files](https://gitlab.bht-berlin.de/sgraupner/ds_cs4bd_2324/-/tree/main/C_expressions)
+from GitLab.
+
+Inspect files and figure out their purpose. Write 1-2 sentenses what each file means
+and purpose is:
+
+ - [__init __.py](https://gitlab.bht-berlin.de/sgraupner/ds_cs4bd_2324/-/blob/main/C_expressions/__init__.py)
+    : `_____________________________________`
+ 
+     - What does the init-file contain?
+     - When and how often is this file executed?
+
+ - [expressions.py](https://gitlab.bht-berlin.de/sgraupner/ds_cs4bd_2324/-/blob/main/C_expressions/expressions.py)
+    : `__________________________________`
+
+ - [test_expressions.py](https://gitlab.bht-berlin.de/sgraupner/ds_cs4bd_2324/-/blob/main/C_expressions/test_expressions.py)
+    : `______________________________`
+
+(1 Pt)
+
+
+&nbsp;
+### 2.) Challenge 2: Run Code
+Run file `expressions.py` in your IDE:
+```
+numbers: [4, 12, 3, 8, 17, 12, 1, 8, 7]
+#
+a) number of numbers: 9
+b) first three numbers: []
+c) last three numbers: []
+d) last three numbers reverse: []
+e) odd numbers: []
+f) number of odd numbers: 0
+g) sum of odd numbers: 0
+h) duplicate numbers removed: []
+i) number of duplicate numbers: 0
+j) ascending, de-dup (n^2) numbers: []
+k) length: NEITHER
+
+[Done] exited with code=0 in 0.126 seconds
+```
+(1 Pt)
+
+Run file `expressions.py` in terminal:
+```sh
+cd <project>                # cd into project directory
+pwd                         # print working directory
+/c/.../workspaces/ds_cs4bd_2324/C_expressions
+
+python expressions.py       # run program
+-->
+numbers: [4, 12, 3, 8, 17, 12, 1, 8, 7]
+a) number of numbers: 9
+b) first three numbers: []
+c) last three numbers: []
+d) last three numbers reverse: []
+e) odd numbers: []
+f) number of odd numbers: 0
+g) sum of odd numbers: 0
+h) duplicate numbers removed: []
+i) number of duplicate numbers: 0
+j) ascending, de-dup (n^2) numbers: []
+k) length: NEITHER
+```
+(1 Pt)
+
+
+&nbsp;
+### 3.) Challenge 3: Run Unit Tests
+Unit Tests are used to *"test-a-unit"* of code in isolation. This unit can be
+a function, a file, a class, a module.
+
+In contrast to running code regularly, Unit Tests execute under the
+supervision of a `test runner` that:
+
+ - looks for (discovers) tested units,
+
+ - executes them with test data, collects test results regardless
+    whether a test succeeded or failed and
+
+ - reports test results at the and.
+
+Read *"A Beginner’s Guide to Unit Tests in Python"*,
+[link](https://www.dataquest.io/blog/unit-tests-python/),
+and answer questions:
+
+ - How are tests discovered? Which feature makes the test runner to collect
+    something as a test?
+
+ - What is an
+    [assert](https://docs.python.org/3/library/unittest.html#assert-methods)
+    statement? What happens when a test (assert) passes and fails?
+
+ - Where is the test runner started in given files?
+
+(1 Pt)
+
+Run tests in a terminal. Currently, only one test runs and passes:
+*TestCase_a_number_of_numbers* :
+```sh
+python test_expressions.py      # run tests directly from file calling the
+                                # test runner in __main__
+```
+
+Output:
+
+```
+test_a_number_of_numbers (C_expressions.test_expressions.TestCase_a_number_of_nu
+mbers.test_a_number_of_numbers) ... ok
+
+----------------------------------------------------------------------
+Ran 1 test in 0.001s
+
+OK
+<unittest.runner.TextTestResult run=1 errors=0 failures=0>
+```
+Result: 1 test was performed that passed.
+
+Alternatively, run tests with test discovery. Run the unit test module that
+starts the test runner, which in turn discovers tests that are then executed:
+
+```sh
+python -m unittest              # let test runner discover tests
+```
+Output is the same as above.
+
+(1 Pt)
+
+Configure your IDE so it also runs Unit Tests. VSCode discovers unit tests under
+the test glass icon (red circled).
+
+The figure shows one unit test that has been discovered passing. Unit tests are
+structured as *"TestCase - Classes"*, which are classes that inherit from class:
+[unittest.TestCase](https://docs.python.org/3/library/unittest.html#unittest.TestCase),
+in the example indirectly through class `Test_case_a`.
+
+VSCode shows discovered test classes in the left panel and their execution result
+with a green check mark when passed or a red cross when failed.
+
+![](../markup/img/C_unit_tests_1.png)
+
+Uncomment tests: *"Test_case_b"* and *"Test_case_c"* in `test_expressions.py`
+above and re-run tests.
+Both tests should fail because expressions they test have not been implemented:
+
+![](../markup/img/C_unit_tests_2.png)
+
+Re-run unit tests with the two tests failing in the terminal:
+
+```sh
+python -m unittest              # let test runner discover tests
+```
+
+Output shows one passing and two failed tests:
+
+```
+======================================================================
+FAIL: test_b_first_three_numbers (test_expressions.TestCase_b_first_three_number
+s.test_b_first_three_numbers)
+----------------------------------------------------------------------
+Traceback (most recent call last):
+  File "C:\Sven1\svgr\workspaces\ds_cs4bd_2324\C_expressions\test_expressions.py
+", line 103, in test_b_first_three_numbers
+    self.assertEqual(self.ut1.b, [4, 12, 3])
+AssertionError: Lists differ: [] != [4, 12, 3]
+
+Second list contains 3 additional elements.
+First extra element 0:
+4
+
+- []
++ [4, 12, 3]
+
+======================================================================
+FAIL: test_c_last_three_numbers (test_expressions.TestCase_c_last_three_numbers.
+test_c_last_three_numbers)
+----------------------------------------------------------------------
+Traceback (most recent call last):
+  File "C:\Sven1\svgr\workspaces\ds_cs4bd_2324\C_expressions\test_expressions.py
+", line 117, in test_c_last_three_numbers
+    td.assertEqual(td.ut1.c, [1, 8, 7])
+AssertionError: Lists differ: [] != [1, 8, 7]
+
+Second list contains 3 additional elements.
+First extra element 0:
+1
+
+- []
++ [1, 8, 7]
+
+----------------------------------------------------------------------
+Ran 3 tests in 0.002s
+
+FAILED (failures=2)
+```
+Output says: `Ran 3 tests`, `FAILED (failures=2)`.
+
+When tests fail, the test report tells which tests have failed and why:
+
+  - *test_b_first_three_numbers* failed in line: 103. The test expected
+    result: `[4, 12, 3]`, but an empty list `[]` was found in the tested
+    expression: `self.b` in file `expressions.py`.
+
+  - *test_c_last_three_numbers* failed in line: 117 where the test expected
+    result: `[1, 8, 7]`, but an empty list `[]` was found in: `self.c`
+
+Tests refer to the `self.numbers` list: `[4, 12, 3, 8, 17, 12, 1, 8, 7]`.
+
+(1 Pt)
+
+
+&nbsp;
+### 4.) Challenge 4: Write Expressions
+
+In order to let tests pass, write expressions in
+[expressions.py](https://gitlab.bht-berlin.de/sgraupner/ds_cs4bd_2324/-/blob/main/C_expressions/expressions.py)
+for variables `self.b` .. `self.k` according to specification, e.g. write an
+expression for `self.b` that extracts the first three numbers from `self.numbers`.
+
+Use <b>one-line expressions</b> only. Built-in functions are allowed, but not
+own functions.
+
+Tests exercise expressions with various lists. Initialization with constants
+(`self.b = [4, 12, 3]`) will hence not work.
+
+Write expression incrementally, one after the other - not all at once. Some
+expressions require thinking and reading.
+
+Once you have written an expression, uncomment the corresponding test case in 
+[test_expressions.py](https://gitlab.bht-berlin.de/sgraupner/ds_cs4bd_2324/-/blob/main/C_expressions/test_expressions.py):
+and re-run the test. See if it is passing or figure out why it is failing
+from the test report.
+
+![](../markup/img/C_unit_tests_3.png)
+
+Test cases a), b) and c) are now passing.
+
+Continue until all tests pass.
+
+![](../markup/img/C_unit_tests_4.png)
+
+
+&nbsp;
+### 5.) Challenge 5: Final Test
+
+Pull latest Unit-test file from GitLab and re-run tests:
+```sh
+wget https://gitlab.bht-berlin.de/sgraupner/ds_cs4bd_2324/-/blob/main/C_express
+ions/test_expressions.py
+
+python test_expressions.py --tests=all
+```
+
+Result:
+
+```
+...........
+----------------------------------------------------------------------
+Ran 11 tests in 0.002s
+
+OK
+<unittest.runner.TextTestResult run=11 errors=0 failures=0>
+```
+(10 Pts, 1 Pt for each test passing)

C_expressions/test_expressions.out

-Run unit tests with discovery (-m) or from __main__() with verbosity level 2
- - python -m unittest test_expressions.py
- - python test_expressions.py
-
-Output with verbosity level < 2:
-================================
-...........
-----------------------------------------------------------------------
-Ran 11 tests in 0.002s
-
-OK
-
-
-Output with verbosity level >=2:
-================================
-test_a_number_of_numbers (C_expressions.test_expressions.TestCase_a_number_of_numbers.test_a_number_of_numbers) ... ok
-test_b_first_three_numbers (C_expressions.test_expressions.TestCase_b_first_three_numbers.test_b_first_three_numbers) ... ok
-test_c_last_three_numbers (C_expressions.test_expressions.TestCase_c_last_three_numbers.test_c_last_three_numbers) ... ok
-test_d_last_threeClass_in_reverse (C_expressions.test_expressions.TestCase_d_last_threeClass_in_reverse.test_d_last_threeClass_in_reverse) ... ok
-test_e_odd_numbers (C_expressions.test_expressions.TestCase_e_odd_numbers.test_e_odd_numbers) ... ok
-test_f_number_of_odd_numbers (C_expressions.test_expressions.TestCase_f_number_of_odd_numbers.test_f_number_of_odd_numbers) ... ok
-test_g_sum_of_odd_numbers (C_expressions.test_expressions.TestCase_g_sum_of_odd_numbers.test_g_sum_of_odd_numbers) ... ok
-test_h_duplicateClass_removed (C_expressions.test_expressions.TestCase_h_duplicateClass_removed.test_h_duplicateClass_removed) ... ok
-test_i_number_of_duplicate_numbers (C_expressions.test_expressions.TestCase_i_number_of_duplicate_numbers.test_i_number_of_duplicate_numbers) ... ok
-test_j_ascending_squaredClass_no_duplicates (C_expressions.test_expressions.TestCase_j_ascending_squaredClass_no_duplicates.test_j_ascending_squaredClass_no_duplicates) ... ok
-test_k_classifyClass_as_odd_even_empty (C_expressions.test_expressions.TestCase_k_classifyClass_as_odd_even_empty.test_k_classifyClass_as_odd_even_empty) ... ok
-----------------------------------------------------------------------
-Ran 11 tests in 0.007s
-
-OK
-<unittest.runner.TextTestResult run=11 errors=0 failures=0>

README.md

@@ -5,6 +5,7 @@ This repository contains the assignments for class
 
 - Assignment A - [Python setup](A_setup_python).
 - Assignment B - [Explore Python](B_explore_python).
+- Assignment C - [Explore Python](C_expressions).